cbfstool: Make endian detection functions to work without prior setup.

The 'host_bigendian' variable (and functions relying on it like ntohl/htonl)
requires host detection by calling static which_endian() first -- which may be
easily forgotten by developers.  It's now a public function in common.c and
doesn't need initialization anymore.

Change-Id: I13dabd1ad15d2d6657137d29138e0878040cb205
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: http://review.coreboot.org/2199
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/util/cbfstool/cbfs-mkstage.c b/util/cbfstool/cbfs-mkstage.c
index ef5182a..4374bda 100644
--- a/util/cbfstool/cbfs-mkstage.c
+++ b/util/cbfstool/cbfs-mkstage.c
@@ -77,7 +77,7 @@
 	if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB) {
 		elf_bigendian = 1;
 	}
-	if (elf_bigendian != host_bigendian) {
+	if (elf_bigendian != is_big_endian()) {
 		elf32_to_native = swap32;
 	}