Support OpenMP on Windows

appveyor.yml

@@ -36,6 +36,7 @@ after_test:
   # Check Qt plugins by following https://wiki.qt.io/Deploy_an_Application_on_Windows
   - set /p VCRedistVersion=<"C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\Microsoft.VCRedistVersion.default.txt"
   - set VCREDIST_CRT_DIR=C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Redist\MSVC\%VCRedistVersion%\%PLATFORM%\Microsoft.VC141.CRT
+  - set VCREDIST_OPENMP_DIR=C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Redist\MSVC\%VCRedistVersion%\%PLATFORM%\Microsoft.VC141.OPENMP
 
   - set TAG=%APPVEYOR_REPO_TAG_NAME%
   - if "%TAG%" == ""
@@ -55,6 +56,7 @@ after_test:
   - 7z a dust3d-%TAG%-%PLATFORM%.zip %QTDIR%\bin\Qt5Network.dll
   - 7z a dust3d-%TAG%-%PLATFORM%.zip "%VCREDIST_CRT_DIR%\msvcp140.dll"
   - 7z a dust3d-%TAG%-%PLATFORM%.zip "%VCREDIST_CRT_DIR%\vcruntime140.dll"
+  - 7z a dust3d-%TAG%-%PLATFORM%.zip "%VCREDIST_OPENMP_DIR%\vcomp140.dll"
   - mkdir platforms
   - copy %QTDIR%\plugins\platforms\qwindows.dll %APPVEYOR_BUILD_FOLDER%\platforms\qwindows.dll
   - 7z a dust3d-%TAG%-%PLATFORM%.zip -r %APPVEYOR_BUILD_FOLDER%\platforms\

dust3d.pro

@@ -503,13 +503,18 @@ INCLUDEPATH += thirdparty/QuadriFlow/3rd/pss
 INCLUDEPATH += thirdparty/QuadriFlow/3rd/lemon-1.3.1
 
 macx: {
-	exists(/usr/local/opt/libomp) {
-#       Install OpenMP: brew install libomp
-		DEFINES += WITH_OMP
-		QMAKE_CXXFLAGS += -Xpreprocessor -fopenmp
-		INCLUDEPATH += /usr/local/opt/libomp/include
-		LIBS += -L/usr/local/opt/libomp/lib -lomp
+	!exists(/usr/local/opt/libomp) {
+		error("Please install OpenMP: brew install libomp")
 	}
+	DEFINES += WITH_OMP
+	QMAKE_CXXFLAGS += -Xpreprocessor -fopenmp
+	INCLUDEPATH += /usr/local/opt/libomp/include
+	LIBS += -L/usr/local/opt/libomp/lib -lomp
+}
+
+win32 {
+	QMAKE_CXXFLAGS += /openmp
+	DEFINES += WITH_OMP
 }
 
 win32 {