disable Qt on macOS for now due to multiple issues

cv2/__init__.py

@@ -19,9 +19,7 @@ except:
     pass
 
 # the Qt plugin is included currently only in the pre-built wheels
-if (
-    sys.platform == "darwin" or sys.platform.startswith("linux")
-) and ci_and_not_headless:
+if sys.platform.startswith("linux") and ci_and_not_headless:
     os.environ["QT_QPA_PLATFORM_PLUGIN_PATH"] = os.path.join(
         os.path.dirname(os.path.abspath(__file__)), "qt", "plugins"
     )

setup.py

@@ -172,7 +172,7 @@ def main():
         if (
             not build_headless
             and "bdist_wheel" in sys.argv
-            and (sys.platform == "darwin" or sys.platform.startswith("linux"))
+            and sys.platform.startswith("linux")
         ):
             cmake_args.append("-DWITH_QT=5")
             subprocess.check_call("patch -p1 < patches/patchQtPlugins", shell=True)

travis_config.sh

@@ -115,15 +115,15 @@ function pre_build {
         brew install ffmpeg_opencv
     fi
 
-    echo 'Installing qt5'
+    # echo 'Installing qt5'
     
-    if [ -n "$CACHE_STAGE" ]; then
-        echo "Qt5 has bottle, no caching needed"
-    else
-        brew switch qt 5.13.2
-        brew pin qt
-        export PATH="/usr/local/opt/qt/bin:$PATH"
-    fi
+    # if [ -n "$CACHE_STAGE" ]; then
+    #    echo "Qt5 has bottle, no caching needed"
+    # else
+    #    brew switch qt 5.13.2
+    #    brew pin qt
+    #    export PATH="/usr/local/opt/qt/bin:$PATH"
+    # fi
 
     if [ -n "$CACHE_STAGE" ]; then
         brew_go_bootstrap_mode 0