message: Fix wrong compiler names
diff: {
  "name": "Generator switch test GCC Make",
  "compilers": {
  - "CXX": "g++.exe",
  - "C": "gcc.exe"
  + "CXX": "g++",
  + "C": "gcc"
  },
  "preferredGenerator": {
  "name": "Unix Makefiles"
  {
  "name": "Generator switch test GCC Ninja",
  "compilers": {
  - "CXX": "g++.exe",
  - "C": "gcc.exe"
  + "CXX": "g++",
  + "C": "gcc"
  },
  "preferredGenerator": {
  "name": "Ninja"
  