ensure em_asm template get C++ linkage

include/pocketpy/export.h

@@ -5,7 +5,6 @@
     #define PK_EXPORT __declspec(dllexport)
     #define PK_SYS_PLATFORM     0
 #elif __EMSCRIPTEN__
-    #include <emscripten.h>
     #define PK_EXPORT EMSCRIPTEN_KEEPALIVE
     #define PK_SYS_PLATFORM     1
 #elif __APPLE__
@@ -31,4 +30,4 @@
 #else
     #define PK_EXPORT
     #define PK_SYS_PLATFORM     6
-#endif
+#endif

include/pocketpy/pocketpy_c.h

@@ -2,6 +2,9 @@
 #define POCKETPY_C_H
 
 #ifdef __cplusplus
+#if __EMSCRIPTEN__
+#include <emscripten.h>
+#endif
 extern "C" {
 #endif