maplibre support for Qt6 and MSVC 2019 (#125)

* [qt] Updating CMake project files for Qt6

* [qt] Updating non-test projects for Qt6 and msvc2019

* [qt] Test fixes for Qt6 and msvc2019

* [qt] Link whole test archive for Qt and msvc2019

* [qt] Fixing Qt6 headless backend renderer

* [qt] Fixes for test failures

* [qt] Expression and style parser test fixes

* [qt] Backwards compatibility with Qt5 and Qt6

Minimum version is Qt 5.4 due to use of QOpenGLWidget

* [qt] LLVM is no longer required for a Windows build

* [msvc] msvc2019 fixes for maplibre

* Update test/storage/offline_database.test.cpp

Co-authored-by: Tadej Novak <tadej@tano.si>

* Vector + const is not standard C++

Co-authored-by: Tadej Novak <tadej@tano.si>

platform/qt/qt.cmake

@@ -1,11 +1,17 @@
 # Note: Using Sqlite instead of QSqlDatabase for better compatibility.
 
-find_package(Qt5Gui REQUIRED)
-find_package(Qt5Network REQUIRED)
-find_package(Qt5OpenGL REQUIRED)
-find_package(Qt5Widgets REQUIRED)
+find_package(Qt${QT_VERSION_MAJOR}
+             COMPONENTS Gui
+                        Network
+                        OpenGL
+                        OpenGLWidgets
+                        Widgets
+             REQUIRED)
 
-if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
+if(MSVC)
+    add_definitions("/DQT_COMPILING_QIMAGE_COMPAT_CPP")
+    add_definitions("/D_USE_MATH_DEFINES")
+elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows")
     add_definitions("-DQT_COMPILING_QIMAGE_COMPAT_CPP")
     add_definitions("-D_USE_MATH_DEFINES")
     add_definitions("-Wno-deprecated-declarations")
@@ -89,10 +95,10 @@ target_link_libraries(
     PRIVATE
         $<$<NOT:$<PLATFORM_ID:Windows>>:z>
         $<$<NOT:$<PLATFORM_ID:Windows>>:mbgl-vendor-icu>
-        Qt5::Core
-        Qt5::Gui
-        Qt5::Network
-        Qt5::OpenGL
+        Qt${QT_VERSION_MAJOR}::Core
+        Qt${QT_VERSION_MAJOR}::Gui
+        Qt${QT_VERSION_MAJOR}::Network
+        Qt${QT_VERSION_MAJOR}::OpenGL
         mbgl-vendor-nunicode
         mbgl-vendor-sqlite
 )
@@ -136,8 +142,8 @@ target_compile_definitions(
 target_link_libraries(
     qmapboxgl
     PRIVATE
-        Qt5::Core
-        Qt5::Gui
+        Qt${QT_VERSION_MAJOR}::Core
+        Qt${QT_VERSION_MAJOR}::Gui
         mbgl-compiler-options
         mbgl-core
 )
@@ -156,8 +162,9 @@ set_property(TARGET mbgl-qt PROPERTY CXX_STANDARD 98)
 target_link_libraries(
     mbgl-qt
     PRIVATE
-        Qt5::Widgets
-        Qt5::Gui
+        Qt${QT_VERSION_MAJOR}::Widgets
+        Qt${QT_VERSION_MAJOR}::Gui
+        Qt${QT_VERSION_MAJOR}::OpenGLWidgets
         mbgl-compiler-options
         qmapboxgl
 )
@@ -177,20 +184,41 @@ target_compile_definitions(
     PRIVATE WORK_DIRECTORY=${PROJECT_SOURCE_DIR}
 )
 
-target_link_libraries(
-    mbgl-test-runner
-    PRIVATE
-        Qt5::Gui
-        Qt5::OpenGL
-        mbgl-compiler-options
-        pthread
-)
+if (MSVC)
+    target_link_libraries(
+        mbgl-test-runner
+        PRIVATE
+            Qt${QT_VERSION_MAJOR}::Widgets
+            Qt${QT_VERSION_MAJOR}::Gui
+            Qt${QT_VERSION_MAJOR}::OpenGL
+            mbgl-compiler-options
+    )
+else()
+    target_link_libraries(
+        mbgl-test-runner
+        PRIVATE
+            Qt${QT_VERSION_MAJOR}::Widgets
+            Qt${QT_VERSION_MAJOR}::Gui
+            Qt${QT_VERSION_MAJOR}::OpenGL
+            mbgl-compiler-options
+            pthread
+    )
+endif()
 
 if(CMAKE_SYSTEM_NAME STREQUAL Darwin)
     target_link_libraries(
         mbgl-test-runner
         PRIVATE -Wl,-force_load mbgl-test
     )
+elseif(MSVC)
+    target_link_options(
+        mbgl-test-runner
+        PRIVATE /WHOLEARCHIVE:../../lib/mbgl-test.lib
+    )
+    target_link_libraries(
+        mbgl-test-runner
+        PRIVATE mbgl-test
+    )
 else()
     target_link_libraries(
         mbgl-test-runner