libpayload: Add unit-tests framework and first test case

This commit adds a unit-tests framework ported from coreboot, and test
for drivers/speaker. Usage of the unit-tests framework is same as for
the coreboot one.

Change-Id: Iaa94ee4dcdc3f74af830113813df0e8fb0b31e4f
Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58242
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Fagerburg <pfagerburg@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>

payloads/libpayload/tests/include/mocks/x86_io.h

@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef TESTS_MOCKS_X86_IO_H_
+#define TESTS_MOCKS_X86_IO_H_
+
+unsigned int inl(int port);
+
+unsigned short inw(int port);
+
+unsigned char inb(int port);
+
+void outl(unsigned int val, int port);
+
+void outw(unsigned short val, int port);
+
+void outb(unsigned char val, int port);
+
+void outsl(int port, const void *addr, unsigned long count);
+
+void outsw(int port, const void *addr, unsigned long count);
+
+void outsb(int port, const void *addr, unsigned long count);
+
+void insl(int port, void *addr, unsigned long count);
+
+void insw(int port, void *addr, unsigned long count);
+
+void insb(int port, void *addr, unsigned long count);
+
+#endif