From: Jan Engelhardt <jengelh@inai.de>
Date: 2016-06-30 13:18:23.962908776 +0200

build: resolve autoreconf warnings

GNUmakefile.am:33: warning: compiling 'sassc.c' with per-target flags requires 'AM_PROG_CC_C_O' in 'configure.ac'
/usr/share/automake-1.13/am/ltlibrary.am: archiver requires 'AM_PROG_AR' in 'configure.ac'

Adding AM_PROG_CC_C_O also requires that no AC_PROG_CC follows it.
Remove the duplicated test, then.

---

Index: libsass-3.4.3/configure.ac
===================================================================
--- libsass-3.4.3.orig/configure.ac
+++ libsass-3.4.3/configure.ac
@@ -16,6 +16,7 @@ m4_ifdef([AM_SILENT_RULES], [AM_SILENT_R
 
 # Checks for programs.
 AC_PROG_CC
+AM_PROG_CC_C_O
 AC_PROG_CXX
 AC_LANG_PUSH([C])
 AC_LANG_PUSH([C++])
@@ -55,7 +56,6 @@ if test "x$is_mingw32" != "xyes"; then
 fi
 
 if test "x$enable_tests" = "xyes"; then
-  AC_PROG_CC
   AC_PROG_AWK
   # test need minitest gem
   AC_PATH_PROG(RUBY, [ruby])