CMake: Improve RCC version-checking

Previously, we check for RCC support every single time CMake runs.
This is slightly wasteful, and it wasn't being done right anyway.
But it's moot because:

- Calamares supports back to Qt 5.9
- Qt 5.9's version of rcc (at least, 5.9.7) **does** support the
  command-line argument `--format-version 1`
- Everything newer does too.

Simplify translations a little, too: just use autorcc rather than
building things by hand.

CMakeModules/CalamaresAddTranslations.cmake

@@ -22,46 +22,14 @@
 
 include( CMakeParseArguments )
 
-if( NOT _rcc_version_support_checked )
-    set( _rcc_version_support_checked TRUE )
-
-    # Extract the executable name
-    get_property( _rcc_executable
-        TARGET ${Qt5Core_RCC_EXECUTABLE}
-        PROPERTY IMPORTED_LOCATION
-    )
-    if( NOT _rcc_executable )
-        # Weird, probably now uses Qt5::rcc which is wrong too
-        set( _rcc_executable ${Qt5Core_RCC_EXECUTABLE} )
-    endif()
-
-    # Try an empty RCC file with explicit format-version
-    execute_process(
-        COMMAND echo "<RCC version='1.0'></RCC>"
-        COMMAND ${Qt5Core_RCC_EXECUTABLE} --format-version 1 --list -
-        RESULT_VARIABLE _rcc_version_rv
-        ERROR_VARIABLE _rcc_version_dump
-    )
-    if ( _rcc_version_rv EQUAL 0 )
-        # Supported: force to the reproducible version
-        set( _rcc_version_support --format-version 1 )
-    else()
-        # Older Qt versions (5.7, 5.8) don't support setting the
-        # rcc format-version, so won't be reproducible if they
-        # default to version 2.
-        set( _rcc_version_support "" )
-    endif()
-    unset( _rcc_version_rv )
-    unset( _rcc_version_dump )
-endif()
-
-
 # Internal macro for adding the C++ / Qt translations to the
 # build and install tree. Should be called only once, from
 # src/calamares/CMakeLists.txt.
 macro(add_calamares_translations language)
     list( APPEND CALAMARES_LANGUAGES ${ARGV} )
 
+    set( _rcc_version_support --format-version 1 )
+
     set( calamares_i18n_qrc_content "<!DOCTYPE RCC><RCC version=\"1.0\">\n" )
 
     # calamares and qt language files

src/calamares/CMakeLists.txt

@@ -34,9 +34,8 @@ include_directories(
 # Translations
 include( CalamaresAddTranslations )
 add_calamares_translations( ${CALAMARES_TRANSLATION_LANGUAGES} )
-qt5_add_resources( calamaresRc calamares.qrc )
 
-add_executable( calamares_bin ${calamaresSources} ${calamaresRc} ${trans_outfile} )
+add_executable( calamares_bin ${calamaresSources} calamares.qrc ${trans_outfile} )
 target_include_directories( calamares_bin PRIVATE ${CMAKE_SOURCE_DIR} )
 set_target_properties(calamares_bin
     PROPERTIES
@@ -45,6 +44,7 @@ set_target_properties(calamares_bin
 )
 calamares_automoc( calamares_bin )
 calamares_autouic( calamares_bin )
+calamares_autorcc( calamares_bin )
 
 target_link_libraries( calamares_bin
     PRIVATE