gcc: Make sure OpenCL tests can be run when STARPU_USE_OPENCL.

* gcc-plugin/tests/mocks.h (starpu_opencl_program): Define only when
  !STARPU_USE_OPENCL.

* gcc-plugin/tests/Makefile.am: Revert r6547 ("when OpenCL is enabled,
  disable tests which use a mock implementation OpenCL as it conflicts
  with the system-installed OpenCL").

gcc-plugin/tests/Makefile.am

@@ -15,20 +15,31 @@
 
 
 gcc_tests =					\
+  base.c					\
+  pointers.c					\
+  output-pointer.c				\
   output-pointer-errors.c			\
+  register.c					\
   register-errors.c				\
+  acquire.c					\
   acquire-errors.c				\
+  release.c					\
   release-errors.c				\
+  unregister.c					\
   unregister-errors.c				\
   task-errors.c					\
   scalar-tasks.c				\
   pointer-tasks.c				\
   external-task-impl.c				\
   no-initialize.c				\
+  lib-user.c					\
   wait-errors.c					\
+  heap-allocated.c				\
   heap-allocated-errors.c			\
   verbose.c					\
   debug-tree.c					\
+  opencl.c					\
+  opencl-errors.c				\
   shutdown-errors.c
 
 EXTRA_DIST =
@@ -42,35 +53,11 @@ gcc_tests += opencl-types.c
 # This test simulates errors when lacking an OpenCL implementation.
 gcc_tests += opencl-lacking.c
 
-gcc_tests +=  					\
-  base.c 					\
-  pointers.c 					\
-  output-pointer.c				\
-  register.c					\
-  acquire.c					\
-  release.c					\
-  unregister.c					\
-  lib-user.c					\
-  heap-allocated.c				\
-  opencl.c					\
-  opencl-errors.c
-
 else STARPU_USE_OPENCL
 
 EXTRA_DIST +=					\
-  base.c					\
-  pointers.c					\
   opencl-types.c				\
-  opencl-lacking.c				\
-  output-pointer.c				\
-  register.c					\
-  acquire.c					\
-  release.c					\
-  unregister.c					\
-  lib-user.c					\
-  heap-allocated.c				\
-  opencl.c					\
-  opencl-errors.c
+  opencl-lacking.c
 
 endif STARPU_USE_OPENCL
 

gcc-plugin/tests/mocks.h

@@ -424,13 +424,19 @@ starpu_free (void *ptr)
 
 /* OpenCL support.  */
 
-#define STARPU_USE_OPENCL 1
+#ifndef STARPU_USE_OPENCL
 
+# define STARPU_USE_OPENCL 1
+
+/* The `opencl' pragma needs this structure, so make sure it's defined.  */
 struct starpu_opencl_program
 {
   /* Nothing.  */
 };
 
+#endif
+
+
 /* Number of `load_opencl_from_string' calls.  */
 static unsigned int load_opencl_calls;