assert.h: add assertions with descriptive failures

BUG=None
TEST=tested in following patches on Trembyle board

Change-Id: Ib30ccd41759e5a2a61d3182cc08ed5eb762eca98
Signed-off-by: Eric Peers <epeers@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1971443
Tested-by: Martin Roth <martinroth@chromium.org>
Reviewed-by: Martin Roth <martinroth@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39620
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

src/include/assert.h

@@ -33,6 +33,17 @@
 			hlt();					\
 	}							\
 }
+
+#define ASSERT_MSG(x, msg) {					\
+	if (!(x)) {						\
+		printk(BIOS_EMERG, "ASSERTION ERROR: file '%s'"	\
+			", line %d\n", __FILE__, __LINE__);	\
+		printk(BIOS_EMERG, "%s", msg);                  \
+		if (CONFIG(FATAL_ASSERTS))			\
+			hlt();					\
+	}							\
+}
+
 #define BUG() {							\
 	printk(BIOS_EMERG, "ERROR: BUG ENCOUNTERED at file '%s'"\
 		", line %d\n", __FILE__, __LINE__);		\