Tests: Fix standalone build of tests with nested projects

Since commit fd6076d0 (Tests: Pass CMAKE_MAKE_PROGRAM instead of
--build-makeprogram, 2013-11-15) the ExportImport, Fortran, and
MacRuntimePath tests use the value of CMAKE_TEST_MAKEPROGRAM as the
CMAKE_MAKE_PROGRAM for their nested projects configurations.
Teach these tests to initialize CMAKE_TEST_MAKEPROGRAM when it is
not provided, such as when building the tests manually.

Tests/ExportImport/CMakeLists.txt

@@ -1,5 +1,8 @@
 cmake_minimum_required (VERSION 2.7.20090711)
 project(ExportImport C CXX)
+if(NOT DEFINED CMAKE_TEST_MAKEPROGRAM AND NOT CMAKE_GENERATOR MATCHES "Visual Studio")
+  set(CMAKE_TEST_MAKEPROGRAM "${CMAKE_MAKE_PROGRAM}")
+endif()
 
 # Wipe out the install tree to make sure the exporter works.
 add_custom_command(

Tests/Fortran/CMakeLists.txt

@@ -1,5 +1,9 @@
 cmake_minimum_required (VERSION 2.6)
 project(testf C CXX Fortran)
+if(NOT DEFINED CMAKE_TEST_MAKEPROGRAM AND NOT CMAKE_GENERATOR MATCHES "Visual Studio")
+  set(CMAKE_TEST_MAKEPROGRAM "${CMAKE_MAKE_PROGRAM}")
+endif()
+
 message("CTEST_FULL_OUTPUT ")
 set(CMAKE_VERBOSE_MAKEFILE 1)
 message("ENV_FLAGS = $ENV{FFLAGS}")

Tests/MacRuntimePath/CMakeLists.txt

@@ -1,6 +1,8 @@
 cmake_minimum_required (VERSION 2.8)
 project(MacRuntimePath)
-
+if(NOT DEFINED CMAKE_TEST_MAKEPROGRAM AND NOT CMAKE_GENERATOR MATCHES "Visual Studio")
+  set(CMAKE_TEST_MAKEPROGRAM "${CMAKE_MAKE_PROGRAM}")
+endif()
 
 # Wipe out the install tree to make sure the exporter works.
 add_custom_command(