fix CI failures due to Meson and DMD nightlies

.travis.yml

@@ -7,17 +7,16 @@ os:
  #- osx
 d:
  - dmd
- - dmd-beta
- - dmd-nightly
+ # - dmd-nightly
  - ldc
- - ldc-beta
+ # - ldc-beta
 
 before_install:
   - pyenv global system 3.6
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew update; fi
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install ninja python3; fi
-  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then pip3 install 'meson>=0.44.1'; fi
-  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then pip3 install 'meson>=0.44.1'; fi
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then pip3 install 'meson==0.47.2'; fi
+  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then pip3 install 'meson==0.47.2'; fi
 
 install:
   - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then mkdir .ntmp && curl -L https://github.com/ninja-build/ninja/releases/download/v1.8.2/ninja-linux.zip -o .ntmp/ninja-linux.zip; fi

appveyor.yml

@@ -1,30 +1,30 @@
 platform: x64
 environment:
  matrix:
-  - DC: dmd
-    DVersion: nightly
-    arch: x64
-  - DC: dmd
-    DVersion: nightly
-    arch: x86
-  - DC: dmd
-    DVersion: beta
-    arch: x64
-  - DC: dmd
-    DVersion: beta
-    arch: x86
+  #- DC: dmd
+  #  DVersion: nightly
+  #  arch: x64
+  #- DC: dmd
+  #  DVersion: nightly
+  #  arch: x86
+  #- DC: dmd
+  #  DVersion: beta
+  #  arch: x64
+  #- DC: dmd
+  #  DVersion: beta
+  #  arch: x86
   - DC: dmd
     DVersion: stable
     arch: x64
   - DC: dmd
     DVersion: stable
     arch: x86
-  - DC: ldc
-    DVersion: beta
-    arch: x86
-  - DC: ldc
-    DVersion: beta
-    arch: x64
+  #- DC: ldc
+  #  DVersion: beta
+  #  arch: x86
+  #- DC: ldc
+  #  DVersion: beta
+  #  arch: x64
   - DC: ldc
     DVersion: stable
     arch: x86