Build of 9base with musl toolchain

# [tuscan]
# Server = file:///var/cache/pacman/pkg/

# :: Synchronizing package databases...
# downloading tuscan.db...

# /sysroot/lib
# /sysroot/share
# /sysroot/bin
# /sysroot/include
# /sysroot/libexec

# ==> Making package: 9base 6-5 (Tue Apr 4 22:53:06 UTC 2017)
# ==> Checking runtime dependencies...
# ==> Checking buildtime dependencies...
# ==> WARNING: Using existing $srcdir/ tree
# ==> Starting build()...
# 9base build options:
# CFLAGS = -DPLAN9PORT -c -I. -DPREFIX="/opt/plan9"
# LDFLAGS =
# CC = cc
# make[1]: Entering directory '/tmp/9base/src/9base-6/lib9'
# CC sec/sha1block.c
# CC sec/sha1.c
# CC sec/sha1pickle.c
# CC sec/md5block.c
# CC sec/md5.c
# CC sec/md5pickle.c
# CC fmt/dofmt.c
# CC fmt/fltfmt.c
# CC fmt/fmt.c
# CC fmt/fmtfd.c
# CC fmt/fmtfdflush.c
# CC fmt/fmtlocale.c
# CC fmtlock2.c
# CC fmt/fmtnull.c
# CC fmt/fmtprint.c
# CC fmt/fmtquote.c
# CC fmt/fmtrune.c
# CC fmt/fmtstr.c
# CC fmt/fmtvprint.c
# CC fmt/fprint.c
# CC fmt/nan64.c
# CC fmt/print.c
# CC fmt/runefmtstr.c
# CC fmt/runeseprint.c
# CC fmt/runesmprint.c
# CC fmt/runesnprint.c
# CC fmt/runesprint.c
# CC fmt/runevseprint.c
# CC fmt/runevsmprint.c
# CC fmt/runevsnprint.c
# CC fmt/seprint.c
# CC fmt/smprint.c
# CC fmt/snprint.c
# CC fmt/sprint.c
# CC fmt/strtod.c
# CC fmt/vfprint.c
# CC fmt/vseprint.c
# CC fmt/vsmprint.c
# CC fmt/vsnprint.c
# CC fmt/charstod.c
# CC fmt/pow10.c
# CC utf/rune.c
# CC utf/runestrcat.c
# CC utf/runestrchr.c
# utf/runestrchr.c:31:11: warning: using the result of an assignment as a condition without parentheses [-Wparentheses]
# while(c1 = *s++)
# ~~~^~~~~~
# CC utf/runestrcmp.c
# CC utf/runestrcpy.c
# utf/runestrcpy.c:25:14: warning: using the result of an assignment as a condition without parentheses [-Wparentheses]
# while(*s1++ = *s2++)
# ~~~~~~^~~~~~~
# CC utf/runestrdup.c
# CC utf/runestrlen.c
# CC utf/runestrecpy.c
# utf/runestrecpy.c:25:14: warning: using the result of an assignment as a condition without parentheses [-Wparentheses]
# while(*s1++ = *s2++){
# ~~~~~~^~~~~~~
# utf/runestrchr.c:31:11: note: place parentheses around the assignment to silence this warningutf/runestrecpy.c
# utf/runestrcpy.c:25::1425: while(c1 = *s++):
# 14note ^::
# place parentheses around the assignment to silence this warning ( )note
#
# : place parentheses around the assignment to silence this warning
# while(*s1++ = *s2++){
# utf/runestrchr.c ^:
# 31 ( ):
# 11: note: while(*s1++ = *s2++)use '==' to turn this assignment into an equality comparison
#
# ^
# while(c1 = *s++) ( )
#
# ^
# ==
# utf/runestrecpy.c:25:14: note: use '==' to turn this assignment into an equality comparison
# while(*s1++ = *s2++){
# ^
# ==
# utf/runestrcpy.c:25:14: note: use '==' to turn this assignment into an equality comparison
# while(*s1++ = *s2++)
# ^
# ==
# 1 warning generated.
# 1 warning generated.
# 1 warning generated.
# CC utf/runestrncat.c
# CC utf/runestrncpy.c
# CC utf/runestrncmp.c
# CC utf/runestrrchr.c
# CC utf/runestrstr.c
# CC utf/runetype.c
# utf/runestrrchr.c:27:10: warning: using the result of an assignment as a condition without parentheses [-Wparentheses]
# while(s = runestrchr(s, c))
# ~~^~~~~~~~~~~~~~~~~~
# utf/runestrrchr.c:27:10: note: place parentheses around the assignment to silence this warning
# while(s = runestrchr(s, c))
# ^
# ( )
# utf/runestrrchr.c:27:10: note: use '==' to turn this assignment into an equality comparison
# while(s = runestrchr(s, c))
# ^
# ==
# utf/runestrncat.c:26:14: warning: using the result of an assignment as a condition without parentheses [-Wparentheses]
# while(*s1++ = *s2++)
# ~~~~~~^~~~~~~
# utf/runestrncat.c:26:14: note: place parentheses around the assignment to silence this warning
# while(*s1++ = *s2++)
# ^
# ( )
# utf/runestrncat.c:26:14: note: use '==' to turn this assignment into an equality comparison
# while(*s1++ = *s2++)
# ^
# ==
# 1 warning generated.
# 1 warning generated.
# CC utf/utfecpy.c
# CC utf/utflen.c
# CC utf/utfnlen.c
# CC utf/utfrrune.c
# CC utf/utfrune.c
# CC utf/utfutf.c
# CC bio/bbuffered.c
# CC bio/bfildes.c
# utf/utfutf.c:37:13: warning: using the result of an assignment as a condition without parentheses [-Wparentheses]
# for(p=s1; p=utfrune(p, f); p+=n1)
# ~^~~~~~~~~~~~~~
# utf/utfutf.c:37:13: note: place parentheses around the assignment to silence this warning
# for(p=s1; p=utfrune(p, f); p+=n1)
# ^
# ( )
# utf/utfutf.c:37:13: note: use '==' to turn this assignment into an equality comparison
# for(p=s1; p=utfrune(p, f); p+=n1)
# ^
# ==
# 1 warning generated.
# CC bio/bflush.c
# CC bio/bgetc.c
# CC bio/bgetrune.c
# CC bio/bgetd.c
# CC bio/binit.c
# CC bio/boffset.c
# CC bio/bprint.c
# CC bio/bputc.c
# CC bio/bputrune.c
# CC bio/brdline.c
# CC bio/brdstr.c
# CC bio/bread.c
# CC bio/bseek.c
# CC bio/bvprint.c
# CC bio/bwrite.c
# CC regex/regcomp.c
# CC regex/regerror.c
# CC regex/regexec.c
# CC regex/regsub.c
# CC regex/regaux.c
# CC regex/rregexec.c
# CC regex/rregsub.c
# CC _exits.c
# CC _p9dialparse.c
# CC _p9dir.c
# CC announce.c
# CC argv0.c
# CC atexit.c
# _p9dir.c:64:10: fatal error: 'linux/hdreg.h' file not found
# #include
# ^
# 1 error generated.
# make[1]: *** [Makefile:225: _p9dir.o] Error 1
# make[1]: *** Waiting for unfinished jobs....
# make[1]: Leaving directory '/tmp/9base/src/9base-6/lib9'
# make: *** [Makefile:63: all] Error 2
# ==> ERROR: A failure occurred in build().
# Aborting...