Suppressing -Wunused-parameter on gcc (just like we do on clang). (#1053)

This fixes various warnings when compiling with -Wextra

Jolt/Core/Core.h

@@ -308,6 +308,7 @@
 	JPH_GCC_SUPPRESS_WARNING("-Winvalid-offsetof")												\
 	JPH_GCC_SUPPRESS_WARNING("-Wclass-memaccess")												\
 	JPH_GCC_SUPPRESS_WARNING("-Wpedantic")														\
+	JPH_GCC_SUPPRESS_WARNING("-Wunused-parameter")												\
 																								\
 	JPH_MSVC_SUPPRESS_WARNING(4619) /* #pragma warning: there is no warning number 'XXXX' */	\
 	JPH_MSVC_SUPPRESS_WARNING(4514) /* 'X' : unreferenced inline function has been removed */	\