tests: Add common test for link_language

It's cool we have a fortran test, but we should have a C/C++ test,
especially for C++ extern "C".

test cases/common/232 link language/c_linkage.cpp

@@ -0,0 +1,5 @@
+extern "C" {
+    int makeInt(void) {
+        return 0;
+    }
+}

test cases/common/232 link language/c_linkage.h

@@ -0,0 +1,10 @@
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int makeInt(void);
+
+#ifdef __cplusplus
+}
+#endif

test cases/common/232 link language/main.c

@@ -0,0 +1,5 @@
+#include "c_linkage.h"
+
+int main(void) {
+    return makeInt();
+}

test cases/common/232 link language/meson.build

@@ -0,0 +1,12 @@
+project(
+  'link_language',
+  ['c', 'cpp'],
+)
+
+exe = executable(
+  'main',
+  ['main.c', 'c_linkage.cpp'],
+  link_language : 'c',
+)
+
+test('main', exe)