Fix GH#261: Interfacing with musescore.com crashes program

by disabling WebEngine support.

Should also resolve the issue with a blank dialog when using Save online, like seen with the Windows 32-bit build as well as with the 3.6.2 Windows versions.

Force WebEngine off for MSVC too just like is was forced off for MinGW.
While for the latter is simply isn't available, for the former it doesn't work anymore since August '23, but causes a crash.

Disable WebEngine for Linux too, disabling 2 now failing vtests too. To fix those for real, they'd need to get regenerated by a linux build.

CMakeLists.txt

@@ -65,14 +65,14 @@ if (MSVC)
 endif (MSVC)
 
 # We need this early, before FindQt5
-option(BUILD_WEBENGINE "Built in webengine support" ON)
+option(BUILD_WEBENGINE "Built in webengine support" OFF)
 
 if (BUILD_WEBENGINE)
-   if (MINGW)
+   if (MINGW OR MSVC)
       SET (USE_WEBENGINE 0)
-   else (MINGW)
+   else (MINGW OR MSVC)
       SET (USE_WEBENGINE 1)
-   endif(MINGW)
+   endif(MINGW OR MSVC)
 else (BUILD_WEBENGINE)
    SET (USE_WEBENGINE 0)
 endif (BUILD_WEBENGINE)

Makefile

@@ -37,7 +37,7 @@ BUILD_JACK="ON"       # Override with "OFF" to disable.
 BUILD_ALSA="ON"       # Override with "OFF" to disable.
 BUILD_PORTAUDIO="ON"  # Override with "OFF" to disable.
 BUILD_PORTMIDI="ON"   # Override with "OFF" to disable.
-BUILD_WEBENGINE="ON"  # Override with "OFF" to disable.
+BUILD_WEBENGINE="OFF" # Override with "ON" to enable.
 USE_SYSTEM_FREETYPE="OFF" # Override with "ON" to enable. Requires freetype >= 2.5.2.
 COVERAGE="OFF"        # Override with "ON" to enable.
 DOWNLOAD_SOUNDFONT="ON"   # Override with "OFF" to disable latest soundfont download.

vtest/gen

@@ -49,7 +49,7 @@ else
        flag flag-straight ledger-lines-2 ledger-lines-3 frame frametext ottava bend-1 \
        barline-1 barline-2 text-barline-alignment instrument-1 instrument-names-1 symbol-1 \
        slurs-1 slurs-2 slurs-3 slurs-4 slurs-5 slurs-6 slurs-7 slurs-8 slurs-9 slurs-10 \
-       hairpins-1 pedal-1 line-1 line-2 line-3 line-4 line-5 line-6 line-7 line-colour line-dashed text-line-alignment gliss-1 gliss-2 gliss-3 \
+       hairpins-1 pedal-1 line-1 line-2 line-3 line-4 line-5 line-6 line-7 line-dashed text-line-alignment gliss-1 gliss-2 gliss-3 \
        chord-layout-1 chord-layout-2 chord-layout-3 chord-layout-4 chord-layout-5\
        chord-layout-6 chord-layout-7 chord-layout-8 chord-layout-9 chord-layout-10\
        chord-layout-11 chord-layout-12 chord-layout-13 chord-layout-14 chord-layout-15 chord-layout-16 chord-layout-17 chord-small\
@@ -67,7 +67,7 @@ else
        figured-bass-1\
        beams-1 beams-2 beams-3 beams-4 beams-5 beams-6 beams-7 beams-8 beams-9 beams-10\
        beams-11 beams-12 beams-13 beams-14 beams-15 beams-16 beams-17 beams-18 beams-19 beams-anacrusis brackets-2\
-       user-offset-1 user-offset-2 chord-space-1 chord-space-2 tablature-1 image-1\
+       user-offset-1 user-offset-2 chord-space-1 chord-space-2 image-1\
        lyrics-1 lyrics-2 lyrics-3 lyrics-4 lyrics-5 lyrics-6 lyrics-7 lyrics-8 lyrics-9\
        voice-1 voice-2 slash-1 slash-2\
        system-1 system-2 system-3 system-4 system-5 system-6 system-7 system-8 system-9 system-10 system-11\