misc: Add a FORCE_NO_ASSERT kconfig directive

The mbedtls test is hitting a compiler bug where two subtests will
soft fail on qemu_xtensa when assertions are enabled.  This is despite
the fact that:

+ The failure is entirely internal to the mbedtls suite.
+ The mbedtls code does not use zephyr asserts
+ The mbedtls code does not call into zephyr code that might assert.
+ The behavior persists even when an irq_lock() is held across the
  entire test, ruling out any asserts in interrupt/exception context.
+ And EVEN WHEN the mbedtls library blobs are bytewise identical
  between assert and non-assert cases.

The bug seems to be a layout thing where the mbedtls code behavior
differently based on code address and/or link-time optimizations
(xtensa has a few).

Unfortunately sanitycheck enables assertions by setting CFLAGS
directly and not via kconfig, so we can't fix this by turning the
feature off in an app right now.  This patch adds a simple "override"
flag that can be set by apps like this that hit bugs.

Again, note that zephyr assertions are not used nor needed by this one
test.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>

include/misc/__assert.h

@@ -67,6 +67,11 @@
 #endif
 #endif
 
+#ifdef CONFIG_FORCE_NO_ASSERT
+#undef __ASSERT_ON
+#define __ASSERT_ON 0
+#endif
+
 #ifdef __ASSERT_ON
 #if (__ASSERT_ON < 0) || (__ASSERT_ON > 2)
 #error "Invalid __ASSERT() level: must be between 0 and 2"

subsys/debug/Kconfig

@@ -104,6 +104,16 @@ config ASSERT_LEVEL
 	  Level 1: on + warning in every file that includes __assert.h
 	  Level 2: on + no warning
 
+config FORCE_NO_ASSERT
+	bool
+	prompt "Force-disable no assertions"
+	default n
+	help
+	  This boolean option disables Zephyr assertion testing even
+	  in circumstances (sanitycheck) where it is enabled via
+	  CFLAGS and not Kconfig.  Added solely to be able to work
+	  around compiler bugs for specific tests.
+
 config OBJECT_TRACING
 	bool
 	prompt "Kernel object tracing"

tests/crypto/mbedtls/prj.conf

@@ -5,3 +5,4 @@ CONFIG_MBEDTLS_BUILTIN=y
 CONFIG_MBEDTLS_CFG_FILE="config-threadnet.h"
 CONFIG_MBEDTLS_TEST=y
 CONFIG_ZTEST=y
+CONFIG_FORCE_NO_ASSERT=y