Add some more autoconf macros to filter our CFLAGS usage

Hopefully these new autoconf macros, with a little magic, will allow us to
compile with any compiler and still choose the options we have available
to us.

Tested locally with gcc 4.2.2 and gcc 3.4.6; the latter doesn't support two
of the items we previously had hardcoded in our CFLAGS.

Signed-off-by: Dan McGee <dan@archlinux.org>

acinclude.m4

@@ -6623,3 +6623,44 @@ AC_DEFUN([GCC_STACK_PROTECT_CC],[
     fi
   fi
 ])
+
+dnl GCC_VISIBILITY_CC
+dnl checks -fvisibility=internal with the C compiler, if it exists then
+dnl defines ENABLE_VISIBILITY_CC in both configure script and Makefiles
+AC_DEFUN([GCC_VISIBILITY_CC],[
+  AC_LANG_ASSERT(C)
+  if test "X$CC" != "X"; then
+    AC_CACHE_CHECK([whether ${CC} accepts -fvisibility=internal],
+      visibility_cv_cc,
+      [visibility_old_cflags="$CFLAGS"
+       CFLAGS="$CFLAGS -fvisibility=internal"
+       AC_TRY_COMPILE(,, visibility_cv_cc=yes, visibility_cv_cc=no)
+       CFLAGS="$visibility_old_cflags"
+      ])
+    if test $visibility_cv_cc = yes; then
+      AC_DEFINE([ENABLE_VISIBILITY_CC], 1, [Define if symbol visibility C support is enabled.])
+    fi
+	AM_CONDITIONAL([ENABLE_VISIBILITY_CC], test "x$visibility_cv_cc" = "xyes")
+  fi
+])
+
+dnl GCC_GNU89_INLINE_CC
+dnl checks -fgnu89-inline with the C compiler, if it exists then defines
+dnl ENABLE_GNU89_INLINE_CC in both configure script and Makefiles
+AC_DEFUN([GCC_GNU89_INLINE_CC],[
+  AC_LANG_ASSERT(C)
+  if test "X$CC" != "X"; then
+    AC_CACHE_CHECK([for -fgnu89-inline],
+    gnu89_inline_cv_cc,
+    [ gnu89_inline_old_cflags="$CFLAGS"
+      CFLAGS="$CFLAGS -fgnu89-inline"
+      AC_TRY_COMPILE(,, gnu89_inline_cv_cc=yes, gnu89_inline_cv_cc=no)
+      CFLAGS="$gnu89_inline_old_cflags"
+    ])
+    if test $gnu89_inline_cv_cc = yes; then
+      AC_DEFINE([ENABLE_GNU89_INLINE_CC], 1, [Define if gnu89 inlining semantics should be used.])
+    fi
+	AM_CONDITIONAL([ENABLE_GNU89_INLINE_CC], test "x$gnu89_inline_cv_cc" = "xyes")
+  fi
+])
+

configure.ac

@@ -162,6 +162,11 @@ AC_CHECK_FUNCS([realpath regcomp strcasecmp strdup strerror strnlen \
 # Enable large file support if available
 AC_SYS_LARGEFILE
 
+# Check if we can use symbol visibility support in GCC
+GCC_VISIBILITY_CC
+# Check if we have -fgnu89-inline flag
+GCC_GNU89_INLINE_CC
+
 # Host-dependant flags
 case "${host}" in
 	*-*-cygwin*)

lib/libalpm/Makefile.am

@@ -7,7 +7,14 @@ include_HEADERS = alpm_list.h alpm.h
 
 DEFS = -DLOCALEDIR=\"@localedir@\" @DEFS@
 
-AM_CFLAGS = -fvisibility=internal -pedantic -D_GNU_SOURCE -fgnu89-inline
+AM_CFLAGS = -pedantic -D_GNU_SOURCE
+
+if ENABLE_VISIBILITY_CC
+AM_CFLAGS += -fvisibility=internal
+endif
+if ENABLE_GNU89_INLINE_CC
+AM_CFLAGS += -fgnu89-inline
+endif
 
 libalpm_la_SOURCES = \
 	add.h add.c \