Add new E_TYPE_XIP to indicate XIP mode (#874)

Emit e_type = E_TYPE_XIP in target info section to indicate that it is
an XIP file, and replace related checks in aot loader.

core/shared/utils/bh_platform.h

@@ -35,4 +35,9 @@
 #define WA_FREE wasm_runtime_free
 #endif
 
+/* The epsilon value is from https://www.cplusplus.com/reference/cfloat/ */
+
+#define WA_FLT_EPSILON 1e-5f
+#define WA_DBL_EPSILON 1e-9
+
 #endif /* #ifndef _BH_PLATFORM_H */