extend global CFLAGS and LDFLAGS to aid distro packaging
extend global CFLAGS and LDFLAGS to aid distro packaging

This preserves globally defined CFLAGS and LDFLAGS and simply
extends those variables to aid distro based packaging toolchains
and predefined distro wide defaults like SSP, relro etc.

Additionally respect the standard variable CC as it could be set for
distros using clang (ot something else) as default compiler.
hashcat/hashcat-utils,hashcat/hashcat-utils,philsmd/hashcat-utils,philsmd/hashcat-utils,hashcat/hashcat-utils