tests/wasm: Add C language as well as C++ language to test

test cases/wasm/1 basic/hello.c

@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+int main() {
+  printf("Hello World\n");
+  return 0;
+}
+

test cases/wasm/1 basic/meson.build

@@ -1,3 +1,4 @@
-project('emcctest', 'cpp')
+project('emcctest', 'c', 'cpp')
 
+executable('hello-c', 'hello.c')
 executable('hello', 'hello.cpp')