update thirdparty, add build script

thirdparty/libpng/.travis.yml

@@ -0,0 +1,41 @@
+branches:
+  except:
+    - /libpng[0-1][0-7]/
+
+language: c
+
+os:
+  - linux
+  - osx
+
+compiler:
+  - clang
+  - gcc
+
+env:
+  - AUTOMATION=cmake CI_NO_TEST=1
+  - AUTOMATION=cmake CI_CMAKE_VARS="-DPNG_HARDWARE_OPTIMIZATIONS=ON" CI_SANITIZERS="address,undefined"
+  - AUTOMATION=cmake CI_CMAKE_VARS="-DPNG_HARDWARE_OPTIMIZATIONS=OFF" CI_SANITIZERS="address,undefined"
+  - AUTOMATION=cmake CI_CMAKE_GENERATOR=Xcode
+  - AUTOMATION=autotools CI_NO_TEST=1
+  - AUTOMATION=autotools CI_CONFIGURE_FLAGS="--enable-hardware-optimizations"
+  - AUTOMATION=autotools CI_CONFIGURE_FLAGS="--disable-hardware-optimizations"
+  - AUTOMATION=legacy CI_NO_TEST=1
+  - AUTOMATION=legacy CI_SANITIZERS="address,undefined"
+
+matrix:
+  exclude:
+    - os: osx
+      compiler: gcc
+    - os: linux
+      env: AUTOMATION=cmake CI_CMAKE_GENERATOR=Xcode
+
+before_script:
+  - 'export CI_CMAKE_BUILD_FLAGS="--parallel 2"'
+  - 'export CI_CTEST_FLAGS="--parallel 2"'
+  - 'export CI_MAKE_FLAGS=-j2'
+  - 'export CI_CC=$TRAVIS_COMPILER'
+  - 'export CI_LEGACY_MAKEFILES="scripts/makefile.$TRAVIS_COMPILER scripts/makefile.std"'
+
+script:
+  - './ci/ci_$AUTOMATION.sh'