Fix miot-mbed compilation, part 2

PUBLISHED_FROM=bd87b901b7c1c1a4f9b0f875f0b024b672121d4a

mongoose.h

@@ -868,7 +868,13 @@ typedef struct stat cs_stat_t;
 #define CS_COMMON_PLATFORMS_PLATFORM_MBED_H_
 #if CS_PLATFORM == CS_P_MBED
 
+/*
+ * mbed.h contains C++ code (e.g. templates), thus, it should be processed
+ * only if included directly to startup file (ex: main.cpp)
+ */
+#ifdef __cplusplus
 /* Amalgamated: #include "mbed.h" */
+#endif
 
 #include <assert.h>
 #include <ctype.h>