Add a build step to test non freetype builds (#6908)

* Add a build step to test non freetype builds

.travis.yml

@@ -70,6 +70,15 @@ matrix:
           sources: &sources
             - llvm-toolchain-trusty-5.0
 
+    - env: PLATFORM=Unix COMPILER=clang-5.0 FREETYPE=0
+      compiler: clang
+      os: linux
+      addons:
+        apt:
+          packages: ['clang-5.0', 'clang++-5.0']
+          sources: &sources
+            - llvm-toolchain-trusty-5.0
+
     - env: PLATFORM=Unix COMPILER=clang-5.0 VALGRIND=1
       compiler: clang
       os: linux

util/travis/script.sh

@@ -22,6 +22,10 @@ if [[ ${PLATFORM} == "Unix" ]]; then
 		CMAKE_FLAGS+=' -DCUSTOM_GETTEXT_PATH=/usr/local/opt/gettext'
 	fi
 
+	if [[ -n "${FREETYPE}" ]] && [[ "${FREETYPE}" == "0" ]]; then
+		CMAKE_FLAGS+=' -DENABLE_FREETYPE=0'
+	fi
+
 	cmake -DCMAKE_BUILD_TYPE=Debug \
 		-DRUN_IN_PLACE=TRUE \
 		-DENABLE_GETTEXT=TRUE \