wasm: add thread-asyncify build variant

Add thread-asyncify build variant for the linux host. This configuration
will be used for running auto-tests, and may also be packaged for
distribution in the installer at a future point in time.

The config options are:
 thread:   -DFEATURE_thread=ON
 asyncify: -DQT_QMAKE_DEVICE_OPTIONS="QT_EMSCRIPTEN_ASYNCIFY=1"

Task-number: QTQAINFRA-4876
Change-Id: Id3ab3134ddd1cb47cf0ae9ac4cd3db239cdde01f
Reviewed-by: David Skoland <david.skoland@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

coin/platform_configs/cmake_platforms_wasm.yaml

@@ -12,6 +12,17 @@ Configurations:
         'CONAN_HOST_PROFILE=coin/conan/profiles/ci-linux-x86_64-gcc-debug-developer',
         'CONAN_PROFILE=coin/conan/profiles/ci-linux-webassembly-x86_64-clang'
     ]
+-
+    Id: 'webassembly-thread-asyncify'
+    Template: 'qtci-linux-openSUSE-15.3-x86_64-50'
+    Target os: 'WebAssembly'
+    Compiler: 'GCC'
+    Platform dependency: 'OpenSUSE-15.3-host'
+    Features: ['Sccache', 'DisableTests']
+    Environment variables: [
+        'EM_CONFIG={{.Env.EMSDK}}/.emscripten',
+        'TARGET_CONFIGURE_ARGS=-DQT_QMAKE_TARGET_MKSPEC=wasm-emscripten -DQT_BUILD_EXAMPLES=OFF -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_C_COMPILER_LAUNCHER=sccache -DCMAKE_CXX_COMPILER_LAUNCHER=sccache -DFEATURE_thread=ON -DQT_QMAKE_DEVICE_OPTIONS="QT_EMSCRIPTEN_ASYNCIFY=1"',
+        'NON_QTBASE_TARGET_CONFIGURE_ARGS=-DCMAKE_C_COMPILER_LAUNCHER=sccache -DCMAKE_CXX_COMPILER_LAUNCHER=sccache']
 -
     Template: 'qtci-windows-10_21H2-x86_64-51'
     Target os: 'WebAssembly'