* gdb.base/langs.exp, gdb.base/langs*: New test.

* gdb.base/Makefile.in: Build it.
	* TODO: Remove item about checking that C names don't get C++
	demangling applied; this test tests it.

gdb/testsuite/gdb.base/langs2.cxx

@@ -0,0 +1,13 @@
+extern "C" int csub (int);
+int
+foo (int x)
+{
+  return csub (x / 2);
+}
+
+extern "C" int cppsub_ (int);
+int
+cppsub_ (int *y)
+{
+  return foo (*y);
+}