Makefile: Fix <LANG>_INCLUDE_WHAT_YOU_USE with CTEST_USE_LAUNCHERS

The 'ctest --launch' command must be placed before the IWYU launcher on
the compiler command line.  Extend the RunCMake.IncludeWhatYouUse test
to cover this case.  The Ninja generator already does it correctly.

Source/cmMakefileTargetGenerator.cxx

@@ -761,13 +761,6 @@ cmMakefileTargetGenerator
       source.GetFullPath(), workingDirectory, compileCommand);
     }
 
-  // Expand placeholders in the commands.
-  for(std::vector<std::string>::iterator i = compileCommands.begin();
-      i != compileCommands.end(); ++i)
-    {
-    this->LocalGenerator->ExpandRuleVariables(*i, vars);
-    }
-
   // Maybe insert an include-what-you-use runner.
   if (!compileCommands.empty() && (lang == "C" || lang == "CXX"))
     {
@@ -782,6 +775,13 @@ cmMakefileTargetGenerator
       }
     }
 
+  // Expand placeholders in the commands.
+  for(std::vector<std::string>::iterator i = compileCommands.begin();
+      i != compileCommands.end(); ++i)
+    {
+    this->LocalGenerator->ExpandRuleVariables(*i, vars);
+    }
+
   // Change the command working directory to the local build tree.
   this->LocalGenerator->CreateCDCommand
     (compileCommands,

Tests/RunCMake/IncludeWhatYouUse/C-launch-Build-stdout.txt

@@ -0,0 +1,4 @@
+Warning: include-what-you-use reported diagnostics:
+should add these lines:
+*
+#include <\.\.\.>

Tests/RunCMake/IncludeWhatYouUse/C-launch.cmake

@@ -0,0 +1,3 @@
+set(CTEST_USE_LAUNCHERS 1)
+include(CTestUseLaunchers)
+include(C.cmake)

Tests/RunCMake/IncludeWhatYouUse/CXX-launch-Build-stdout.txt

@@ -0,0 +1,4 @@
+Warning: include-what-you-use reported diagnostics:
+should add these lines:
+*
+#include <\.\.\.>

Tests/RunCMake/IncludeWhatYouUse/CXX-launch.cmake

@@ -0,0 +1,3 @@
+set(CTEST_USE_LAUNCHERS 1)
+include(CTestUseLaunchers)
+include(CXX.cmake)

Tests/RunCMake/IncludeWhatYouUse/RunCMakeTest.cmake

@@ -16,3 +16,7 @@ endfunction()
 
 run_iwyu(C)
 run_iwyu(CXX)
+if (NOT RunCMake_GENERATOR STREQUAL "Watcom WMake")
+  run_iwyu(C-launch)
+  run_iwyu(CXX-launch)
+endif()