toolchain: define __no_optimization attribute across toolchains

The __attribute__((optimize("-O0"))) attribute is used to disable
optimization of some test functions. ARC MWDT toolchain doesn't
support it, however it supports __attribute__((optnone)) with
similar functionality.

Define __no_optimization attribute across all toolchains so it
can be used in tests.

NOTE: we don't define __no_optimization for XCC as it includes
GCC header with __no_optimization defined.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>

include/toolchain/gcc.h

@@ -194,6 +194,10 @@ do {                                                                    \
 
 #define popcount(x) __builtin_popcount(x)
 
+#ifndef __no_optimization
+#define __no_optimization __attribute__((optimize("-O0")))
+#endif
+
 #ifndef __weak
 #define __weak __attribute__((__weak__))
 #endif

include/toolchain/mwdt.h

@@ -61,6 +61,8 @@
 
 #else /* defined(_ASMLANGUAGE) */
 
+#define __no_optimization __attribute__((optnone))
+
 #include <toolchain/gcc.h>
 
 /* Metaware toolchain has _Static_assert. However it not able to calculate

tests/kernel/gen_isr_table/src/main.c

@@ -160,7 +160,7 @@ void isr6(const void *param)
  * doesn't support this; we need to tell the compiler not to reorder memory
  * accesses to trigger_check around calls to trigger_irq.
  */
-__attribute__((optimize("-O0")))
+__no_optimization
 #endif
 int test_irq(int offset)
 {