Adjust CI configuration to call the unified build script

.travis.yml

@@ -52,5 +52,4 @@ before_install:
   - if [ "$TRAVIS_OS_NAME" == "osx" ]; then brew install libffi gettext glib pixman pkg-config autoconf pixman sdl2 libepoxy; fi
 
 script:
-  - if [ "$TRAVIS_OS_NAME" == "osx" ]; then ./build_macos.sh ; fi
-  - if [ "$TRAVIS_OS_NAME" == "linux" ]; then ./build_linux.sh ; fi
+  - ./build.sh

appveyor.bat

@@ -35,4 +35,4 @@ set CHERE_INVOKING=yes
 rem Build/test scripting
 bash -xlc "set pwd"
 bash -xlc "env"
-bash -xlc "./build_windows.sh"
+bash -xlc "./build.sh"