fix setup.py and try speed up the build on MacOS/Linux

Author: skvark

setup.py

@@ -8,8 +8,20 @@
 contrib_build = False
 package_name = "opencv-python"
 
-if int(os.getenv('ENABLE_CONTRIB', 0)) == 1:
-    contrib_build = True
+contrib = os.getenv('ENABLE_CONTRIB', None)
+
+if contrib is not None:
+    if int(contrib) == 1:
+        contrib_build = True
+else:
+    try:
+        print("Trying to read contrib enable flag from file...")
+        with open("contrib.enabled") as f:
+            flag = int(f.read(1))
+            if flag == 1:
+                contrib_build = True
+    except:
+        pass
 
 if contrib_build:
     package_name = "opencv-contrib-python"

travis/build-wheels-osx.sh

@@ -107,7 +107,7 @@ fi
 
 
 echo 'Begin build'
-make -j4
+make -j2
 
 # Moving back to opencv-python
 cd ../..

travis/build-wheels.sh

@@ -72,12 +72,12 @@ for PYBIN in /opt/python/cp$PYTHON_VERSION*/bin; do
 
     if [[ $PYTHON_VERSION == 2* ]]; then
       echo 'Build for Py2'
-      (cd build; make -j5 opencv_python2)
+      (cd build; make -j2 opencv_python2)
     fi
 
     if [[ $PYTHON_VERSION == 3* ]]; then
       echo 'Build for Py3'
-      (cd build; make -j5 opencv_python3)
+      (cd build; make -j2 opencv_python3)
     fi