[qt] Build with WebAssembly (#256)

platform/default/src/mbgl/storage/mbtiles_file_source.cpp

@@ -17,7 +17,7 @@
 
 #include <mbgl/storage/sqlite3.hpp>
 
-#if defined(__QT__) && defined(_WIN32)
+#if defined(__QT__) && (defined(_WIN32) || defined(__EMSCRIPTEN__))
 #include <QtZlib/zlib.h>
 #else
 #include <zlib.h>

platform/default/src/mbgl/util/compression.cpp

@@ -1,6 +1,6 @@
 #include <mbgl/util/compression.hpp>
 
-#if defined(__QT__) && defined(_WIN32)
+#if defined(__QT__) && (defined(_WIN32) || defined(__EMSCRIPTEN__))
 #include <QtZlib/zlib.h>
 #else
 #include <zlib.h>

platform/qt/qt.cmake

@@ -150,7 +150,7 @@ set_property(TARGET mbgl-core PROPERTY AUTOMOC ON)
 target_link_libraries(
     mbgl-core
     PRIVATE
-        $<$<NOT:$<PLATFORM_ID:Windows>>:z>
+        $<$<NOT:$<PLATFORM_ID:Windows,Emscripten>>:z>
         Qt${QT_VERSION_MAJOR}::Core
         Qt${QT_VERSION_MAJOR}::Gui
         Qt${QT_VERSION_MAJOR}::Network
@@ -294,6 +294,10 @@ if(NOT MBGL_QT_LIBRARY_ONLY)
         ${PROJECT_SOURCE_DIR}/platform/qt/resources/common.qrc
     )
 
+    if(CMAKE_SYSTEM_NAME STREQUAL "Emscripten")
+        set(CMAKE_EXECUTABLE_SUFFIX ".html")
+    endif()
+
     # Qt public API should keep compatibility with old compilers for legacy systems
     set_property(TARGET mbgl-qt PROPERTY CXX_STANDARD 98)
     set_property(TARGET mbgl-qt PROPERTY AUTOMOC ON)