Fix unrecognized option errors when building with older versions of GCC (Issue #23).

This approach suggested by ppannuto.
Clean up GCC flags

Remove some redundant or repeated flags, as noted by ppannuto in Issue #23.
Clean up Makefile success output
Remove Redis objects on make clean

Resolves Issue #33.
Undefine _FORTIFY_SOURCE before defining it, in case it's set by the distro.

Fixes Issue #7.
remove redundant -Ws from Makefile
Install man files under $(PREFIX)
$(EXTRA_CFLAGS) FOR RPM %{optflags}

We RPM packaging system need to use optflags for secure building, and of course will override the flags you've defined.

However the current one is not good, we should leave it to the end of the flags queue.

[rpmaker@fab SPECS]$ rpm -E %{optflags}
-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches  -m32 -march=i686 -mtune=atom -fasynchronous-unwind-tables
fixing header guards close issue #48
fixing .h protectors in lib/*
Merge branch 'patch-2' of github.com:cicku/zmap into cicku-patch-2
Merge branch 'master' of github.com:jimcheetham/zmap into jimcheetham-master
 removing simple and extended file modules
merging in master