Conditionalize the Rust support regression test

* tests/test-diff-dwarf.cc: Run the rust support regression test
	only if we support Rust on the platform.
	* tests/test-utils.h: Include config.h.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>

tests/test-diff-dwarf.cc

@@ -344,12 +344,14 @@ InOutSpec in_out_specs[] =
     "data/test-diff-dwarf/test45-anon-dm-change-report-0.txt",
     "output/test-diff-dwarf/test45-anon-dm-change-report-0.txt"
   },
+#ifdef HAVE_DW_LANG_Rust_enumerator
   {
     "data/test-diff-dwarf/test46-rust-libone.so",
     "data/test-diff-dwarf/test46-rust-libtwo.so",
     "data/test-diff-dwarf/test46-rust-report-0.txt",
     "output/test-diff-dwarf/test46-rust-report-0.txt"
   },
+#endif
   // This should be the last entry
   {NULL, NULL, NULL, NULL}
 };

tests/test-utils.h

@@ -21,6 +21,7 @@
 #ifndef __TEST_UTILS_H__
 #define __TEST_UTILS_H__
 
+#include "config.h"
 #include <string>
 
 namespace abigail