Also install parser.g to Qt prefix

Change-Id: Iba200b971055cd03a35903a4a233bfffb7b05163
Reviewed-by: Allen Winter <allen.winter@kdab.com>
Reviewed-by: Brett Stottlemyer <bstottle@ford.com>

src/repparser/repparser.pro

@@ -16,6 +16,10 @@ QMAKE_EXTRA_COMPILERS += copy_files
 EXTRA_HEADERS += \
     $$PWD/parser.g
 
+extra_headers.files = $$EXTRA_HEADERS
+extra_headers.path = $$[QT_INSTALL_HEADERS]/$$MODULE_INCNAME
+INSTALLS += extra_headers
+
 PUBLIC_HEADERS += \
     $$PWD/qrepregexparser.h