append $Config{ccflags} to CCFLAGS

This makes it possible for binary distributions to rebuild the module
if perl's $Config{ccflags} is changed for whatever reason. Without
this appending, binary compatibility can't be guaranteed.

http://bugs.debian.org/643038

Makefile.PL

@@ -158,7 +158,7 @@ my %MakeParams = (
     VERSION_FROM => 'Firebird.pm',                              # finds $VERSION
     C            => ['dbdimp.c'],
     H            => [ 'dbdimp.h', 'Firebird.h' ],
-    CCFLAGS      => '-Wall -fno-strict-aliasing',
+    CCFLAGS      => "-Wall -fno-strict-aliasing $Config{ccflags}",
     INC          => qq(-I"$fb_INC" -I"$dbi_arch_dir"),
     OBJECT       => "Firebird.o dbdimp.o",
     LIBS         => [''],