[cov] Add OT_NO_COVERAGE attribute macro

This macro allows marking functions to be excluded from coverage
instrumentation, which is useful for functions that are called in contexts
where coverage instrumentation would cause issues.

Change-Id: I0163ca4d132f2f58f287c84b773fdd5b5d1e7f76
Signed-off-by: Yi-Hsuan Deng <[email protected]>

Author: sasdf

sw/device/lib/base/macros.h

@@ -750,4 +750,9 @@ class SignConverter {
   })
 #endif
 
+/**
+ * Attribute on function declarations to disable coverage instrumentation.
+ */
+#define OT_NO_COVERAGE __attribute__((no_profile_instrument_function))
+
 #endif  // OPENTITAN_SW_DEVICE_LIB_BASE_MACROS_H_