- updated Travis configuration

Enabled usage of embedded thirdparty libraries to make sure that they are in buildable state
Added GTK+ version 2 or 3 as dependency to each Linux target

.travis.yml

@@ -32,6 +32,7 @@ matrix:
           packages:
             - g++-4.9
             - libsdl2-dev
+            - libgtk2.0-dev
 
     - os: linux
       compiler: gcc
@@ -45,6 +46,7 @@ matrix:
           packages:
             - g++-5
             - libsdl2-dev
+            - libgtk-3-dev
 
     - os: linux
       compiler: gcc
@@ -58,6 +60,7 @@ matrix:
           packages:
             - g++-6
             - libsdl2-dev
+            - libgtk2.0-dev
 
     - os: linux
       compiler: gcc
@@ -71,6 +74,7 @@ matrix:
           packages:
             - g++-7
             - libsdl2-dev
+            - libgtk-3-dev
 
     - os: linux
       compiler: clang
@@ -103,7 +107,14 @@ script:
   - echo ${TRAVIS_BUILD_DIR}
   - mkdir build
   - cd build
-  - cmake ${CMAKE_OPTIONS} -DPK3_QUIET_ZIPDIR=YES ..
+  - >
+    cmake ${CMAKE_OPTIONS}       \
+      -DFORCE_INTERNAL_ZLIB=YES  \
+      -DFORCE_INTERNAL_JPEG=YES  \
+      -DFORCE_INTERNAL_BZIP2=YES \
+      -DFORCE_INTERNAL_GME=YES   \
+      -DPK3_QUIET_ZIPDIR=YES     \
+      ..
   - make -j2 -k
 
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