Allow cross compilers to set compiler.

Resolves #68. Based on alex-eri @ github patch.

Author: aabc

configure

@@ -154,9 +154,9 @@ iptables_find_version() {
 
 compiler_presence_test() {
   echo -n "Check for working gcc: "
-  gcc -v >/dev/null 2>&1
+  $CC -v >/dev/null 2>&1
   if [ $? = 0 ]; then
-    echo Yes
+    echo Yes "($CC)"
   else
     echo No
 
@@ -197,7 +197,7 @@ compile_libitp_test() {
   echo "
 #define __EXPORTED_HEADERS__
 #include <$*>" > test.c
-  gcc -c test.c $FLAGS >/dev/null 2>&1
+  $CC -c test.c $FLAGS >/dev/null 2>&1
   RET=$?
   if [ $RET = 0 ]; then
     echo Yes $MSG;
@@ -593,6 +593,7 @@ kernel_check_consistency
 kernel_check_config
 kernel_check_features
 
+CC=${CC:-gcc}
 test "$IPTBIN" || IPTBIN=`which iptables`
 
 iptables_find_version	#IPTVER