-Wno-unused-result now added only on gcc >= 4.4

This option does not exist in gcc 4.3 and earlier, and it breaks the build on
systems with older compilers. The makefile has been enhanced to test for the
version and adds it only if a newer compiler is detected.

Makefile

@@ -13,7 +13,18 @@ LDFLAGS_P=$(LDFLAGS)
 ifneq ($(GCC_MAJOR),2)
 CFLAGS+=-fno-strict-aliasing
 ifneq ($(GCC_MAJOR),3)
-CFLAGS+=-Wno-pointer-sign -Wno-sign-compare -Wno-unused-result
+CFLAGS+=-Wno-pointer-sign -Wno-sign-compare
+
+# add -Wno-unused-result only on gcc >= 4.4
+ifeq ($(GCC_MAJOR),4)
+GCCGREATERTHEN44 := $(shell expr `gcc -dumpversion | cut -f2 -d.` \>= 4)
+else
+GCCGREATERTHEN44 := 1
+endif
+ifeq ($(GCCGREATERTHEN44),1)
+CFLAGS+=-Wno-unused-result
+endif
+
 endif
 endif