Allow disabling "inline"

Compiler support for inline is sometimes buggy, and occasionally
missing entirely.  This patch adds a test for inline support, and
redefines the keyword with the preprocessor if necessary at compile
time.

Signed-off-by: Gary V. Vaughan <gary@thewrittenword.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -11,6 +11,9 @@ all::
 # Define SOCKLEN_T to a suitable type (such as 'size_t') if your
 # system headers do not define a socklen_t type.
 #
+# Define INLINE to a suitable substitute (such as '__inline' or '') if git
+# fails to compile with errors about undefined inline functions or similar.
+#
 # Define SNPRINTF_RETURNS_BOGUS if your are on a system which snprintf()
 # or vsnprintf() return -1 instead of number of characters which would
 # have been written to the final string if enough space had been available.
@@ -1090,6 +1093,10 @@ else
 BROKEN_PATH_FIX = '/^\# @@BROKEN_PATH_FIX@@$$/d'
 endif
 
+ifneq (,$(INLINE))
+	BASIC_CFLAGS += -Dinline=$(INLINE)
+endif
+
 ifneq (,$(SOCKLEN_T))
 	BASIC_CFLAGS += -Dsocklen_t=$(SOCKLEN_T)
 endif

config.mak.in

@@ -58,6 +58,7 @@ NO_INET_PTON=@NO_INET_PTON@
 NO_ICONV=@NO_ICONV@
 OLD_ICONV=@OLD_ICONV@
 NO_DEFLATE_BOUND=@NO_DEFLATE_BOUND@
+INLINE=@INLINE@
 SOCKLEN_T=@SOCKLEN_T@
 FREAD_READS_DIRECTORIES=@FREAD_READS_DIRECTORIES@
 SNPRINTF_RETURNS_BOGUS=@SNPRINTF_RETURNS_BOGUS@

configure.ac

@@ -327,6 +327,12 @@ GIT_PARSE_WITH(tcltk))
 AC_MSG_NOTICE([CHECKS for programs])
 #
 AC_PROG_CC([cc gcc])
+AC_C_INLINE
+case $ac_cv_c_inline in
+  inline | yes | no)	;;
+  *)			AC_SUBST([INLINE], [$ac_cv_c_inline]) ;;
+esac
+
 # which switch to pass runtime path to dynamic libraries to the linker
 AC_CACHE_CHECK([if linker supports -R], git_cv_ld_dashr, [
    SAVE_LDFLAGS="${LDFLAGS}"