qmake function str_member incorrectly parsed GCC version.

GCC 11 returned as GCC 1.

common.pri

@@ -16,8 +16,9 @@ win32{
 unix{
     *g++* {
         GCC_VERSION = $$system("g++ -dumpfullversion -dumpversion")
-        message("g++ version $$GCC_VERSION found")
-        COMPILER_MAJOR_VERSION = $$str_member($${GCC_VERSION})
+        GCC_VERSIONS = $$split(GCC_VERSION, ".")
+        COMPILER_MAJOR_VERSION = $$member(GCC_VERSIONS, 0)
+        message("g++ version $${COMPILER_MAJOR_VERSION}.x found")
 
         greaterThan(COMPILER_MAJOR_VERSION, 3):CONFIG += g++4
         greaterThan(COMPILER_MAJOR_VERSION, 4):CONFIG += g++5
@@ -416,16 +417,12 @@ g++6:GCC_DEBUG_CXXFLAGS += \
     -Wmisleading-indentation
 
 # Since GCC 7
-g++7{
-    GCC_DEBUG_CXXFLAGS += \
-        -Wduplicated-branches \
-        -Wrestrict \
-        -Walloc-zero \
-        -Wnonnull \
-        -Wno-stringop-overflow # cannot suppress warning in Qt headers
-
-    QMAKE_CXXFLAGS_WARN_ON += -Wno-stringop-overflow # cannot suppress warning in Qt headers
-}
+g++7:GCC_DEBUG_CXXFLAGS += \
+    -Wduplicated-branches \
+    -Wrestrict \
+    -Walloc-zero \
+    -Wnonnull \
+    -Wno-stringop-overflow # cannot suppress warning in Qt headers
 
 # Since GCC 8
 g++8:GCC_DEBUG_CXXFLAGS += \