[MIPS] Update build rules

Add  -D_FORTIFY_SOURCE=1 to the default cflags
Update build rule for executable with PRIVATE_ALL_WHOLE_STATIC_LIBRARIES
Use single dash version of -print-whatever
compile everything with relro / bind_now
Enable NX protections

Some other cleanups to reduce differences between ARM and MIPS config files

Change-Id: I30b4de449e6353b581ef7f9437a3bb9be53d5bbf
Signed-off-by: Chris Dearman <chris@mips.com>