Remove legacy include (for ubuntu precise)

.ci/ogc/build.sh

@@ -22,7 +22,6 @@ cmake -GNinja \
  -DWITH_3D=OFF \
  -DWITH_STAGED_PLUGINS=OFF \
  -DWITH_GRASS=OFF \
- -DSUPPRESS_QT_WARNINGS=ON \
  -DENABLE_MODELTEST=OFF \
  -DENABLE_PGTEST=OFF \
  -DENABLE_MSSQLTEST=OFF \

.docker/docker-qgis-build.sh

@@ -90,7 +90,6 @@ cmake \
  -DWITH_GRASS7=${WITH_GRASS7} \
  -DWITH_GRASS8=${WITH_GRASS8} \
  -DWITH_GRASS_PLUGIN=${WITH_GRASS8} \
- -DSUPPRESS_QT_WARNINGS=ON \
  -DENABLE_TESTS=ON \
  -DENABLE_MODELTEST=${WITH_QT5} \
  -DENABLE_PGTEST=${WITH_QT5} \

.docker/qgis.dockerfile

@@ -42,7 +42,6 @@ RUN SUCCESS=OK \
   -DBINDINGS_GLOBAL_INSTALL=ON \
   -DWITH_STAGED_PLUGINS=ON \
   -DWITH_GRASS=ON \
-  -DSUPPRESS_QT_WARNINGS=ON \
   -DDISABLE_DEPRECATED=ON \
   -DENABLE_TESTS=OFF \
   -DWITH_QSPATIALITE=ON \

CMakeLists.txt

@@ -675,13 +675,6 @@ if(WITH_CORE)
     find_package(Libtasn1 REQUIRED)
   endif()
 
-  if (SUPPRESS_QT_WARNINGS)
-    # Newer versions of UseQt4.cmake include Qt with -isystem automatically
-    # This can be used to force this behavior on older systems
-    # Can be removed as soon as Travis-CI updates from precise
-    include_directories(SYSTEM ${QT_INCLUDE_DIR})
-  endif()
-
   # Disable automatic conversion from QString to ASCII 8-bit strings (char *)
   # (Keeps code compatible with Qt/Mac/64bit)
   add_definitions(-DQT_NO_CAST_TO_ASCII)