assert.h: add support for static_assert per c spec

The static_assert documentation:

https://en.cppreference.com/w/c/language/_Static_assert

says one can include assert.h to get the necessary build glue until C23;
add support for this so legacy code builds.

Change-Id: I5cf19b84d3263f3893498f1a07ca7c9e14f547fa

sdk/include/assert.h

diff --git a/sdk/include/assert.h b/sdk/include/assert.h
index 5f3dd9c..4e83e5d 100644
--- a/sdk/include/assert.h
+++ b/sdk/include/assert.h
@@ -12,4 +12,8 @@
 #	define assert(x) ((x) ? (void)0 : panic())
 #endif
 
+#ifndef static_assert
+#define static_assert _Static_assert
+#endif
+
 #endif // _ASSERT_H_