Improve compiler detection.

--HG--
branch : develop

Valentina.pro

@@ -15,6 +15,11 @@ count(LIST, 1, >): error("The build will fail. Path '$${OUT_PWD}' contains space
 
 unix {
     *g++* {
+        GCC_VERSION = $$system("g++ -dumpversion")
+        contains(GCC_VERSION, ^9.*$) {
+            message( "g++ version 9.x found" )
+            CONFIG += g++9
+        } else {
             GCC_VERSION = $$system("g++ -dumpversion")
             contains(GCC_VERSION, ^8.*$) {
                 message( "g++ version 8.x found" )
@@ -44,6 +49,7 @@ unix {
             }
         }
     }
+}
 
 TEMPLATE = subdirs
 SUBDIRS = src