Add webAssembly build for windows again

This reverts commit 9a8fb868ec
partially.

See also 38e416be66.

Task-number: QTBUG-63917
Task-number: QTQAINFRA-2835
Change-Id: I6a63c2c437bd1568d88ffae0b565b99c15188770
Reviewed-by: Liang Qi <liang.qi@qt.io>

coin/platform_configs/qt5.yaml

@@ -156,6 +156,12 @@
     Compiler: 'GCC'
     Features: ['Packaging', 'DisableTests']
     Configure arguments: '-opensource -confirm-license -verbose -prefix /home/qt/work/install -release -nomake tests -nomake examples -no-sql-mysql -no-use-gold-linker -opengl es2 -qpa qnx -xplatform qnx-x86-64-qcc'
+-
+    Template: 'qtci-windows-10-x86_64-14'
+    Target os: 'WebAssembly'
+    Compiler: 'Mingw73'
+    Features: ['Packaging', 'DisableTests']
+    Configure arguments: '-opensource -confirm-license -verbose -prefix c:\Users\qt\work\install -release -nomake examples -nomake tests -no-feature-thread -static -no-dbus -no-headersclean -no-ssl -no-warnings-are-errors -no-pch -platform win32-g++ -xplatform wasm-emscripten'
 -
     Template: 'qtci-macos-10.13-x86_64-2'
     Target os: 'WebAssembly'