cbmem compilation needs to use the hardened toolchain

The appropriate compiler (provided by the build system) is used to
ensure proper toolchain options are used.

cbmem.c is being modified to suppress pointer to integer typecast
warnings.

Change-Id: Ibab2faacbd7bdfcf617ce9ea4296ebe7d7b64562
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: http://review.coreboot.org/1791
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

util/cbmem/cbmem.c

@@ -125,7 +125,7 @@ static const struct timestamp_table *find_tstamps(u64 address)
 				int new_size;
 				struct timestamp_table *tst_p;
 				u32 stamp_addr = (u32)
-					((u64)cbmr_p->cbmem_addr);
+					((uintptr_t)(cbmr_p->cbmem_addr));
 
 				readmem(buf, stamp_addr,
 					sizeof(struct timestamp_table));