Always place try_compile executables predictably (#11724)

Set CMAKE_RUNTIME_OUTPUT_DIRECTORY explicitly in try_compile projects so
that the COPY_FILE feature knows where to look.  This makes the feature
robust against CMAKE_USER_MAKE_RULES_OVERRIDE files that set variables
like CMAKE_RUNTIME_OUTPUT_DIRECTORY or EXECUTABLE_OUTPUT_PATH.

Source/cmCoreTryCompile.cxx

@@ -277,6 +277,10 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv)
       cmakeFlags.push_back(flag);
       }
 
+    /* Put the executable at a known location (for COPY_FILE).  */
+    fprintf(fout, "SET(CMAKE_RUNTIME_OUTPUT_DIRECTORY \"%s\")\n",
+            this->BinaryDirectory.c_str());
+    /* Create the actual executable.  */
     fprintf(fout, "ADD_EXECUTABLE(cmTryCompileExec \"%s\")\n",source.c_str());
     fprintf(fout, 
             "TARGET_LINK_LIBRARIES(cmTryCompileExec ${LINK_LIBRARIES})\n");