CMake: Use intelcet flags for bootstrap and qmake

This should fix build failures on Ubuntu 20.04.

Amends fa98adbd04

Change-Id: Iff399faff0cf06f5b88d756b1f632b8798069578
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

cmake/QtBuild.cmake

@@ -1494,6 +1494,25 @@ function(qt_internal_apply_gc_binaries target visibility)
     endif()
 endfunction()
 
+function(qt_internal_apply_intel_cet target visibility)
+    if(NOT QT_FEATURE_intelcet)
+        return()
+    endif()
+
+    set(possible_visibilities PRIVATE INTERFACE PUBLIC)
+    list(FIND possible_visibilities "${visibility}" known_visibility)
+    if (known_visibility EQUAL "-1")
+        message(FATAL_ERROR "Visibitily setting must be one of PRIVATE, INTERFACE or PUBLIC.")
+    endif()
+
+    if(GCC)
+        set(flags "-mshstk")
+    endif()
+    if(flags)
+        target_compile_options("${target}" ${visibility} "${flags}")
+    endif()
+endfunction()
+
 function(qt_internal_add_linker_version_script target)
     qt_parse_all_arguments(arg "qt_internal_add_linker" "INTERNAL" "" "PRIVATE_HEADERS" ${ARGN})
 

qmake/CMakeLists.txt

@@ -274,3 +274,4 @@ qt_internal_apply_gc_binaries(${target_name} PRIVATE) # special case
 
 qt_enable_msvc_cplusplus_define(${target_name} PUBLIC) # special case
 qt_skip_warnings_are_errors(${target_name}) # special case
+qt_internal_apply_intel_cet(Bootstrap PUBLIC) # special case

src/tools/bootstrap/CMakeLists.txt

@@ -265,4 +265,5 @@ qt_internal_apply_gc_binaries(Bootstrap PUBLIC)
 set_target_properties(Bootstrap PROPERTIES AUTOMOC OFF AUTOUIC OFF AUTORCC OFF)
 qt_internal_add_target_aliases(Bootstrap)
 qt_enable_msvc_cplusplus_define(Bootstrap PUBLIC)
+qt_internal_apply_intel_cet(Bootstrap PUBLIC)
 # special case end