qmltypes.prf uses $$lower (e.g. "TARGET_BASENAME = $$lower($$basename(TARGET))" which breaks building while using qmltyperegistrar tool on a case-sensitive filesystem

Hi, since Qt 5.6 there is "CONFIG *= file_copies" undocumented feature, which, as far as I know, many developers found pleasant as an INSTALL alternative or extra compiler feature doing just file copying.

The issue a met occurs on case sensitive filesystem for an ordinal QML app, containing the following key fragment in its pro-file:

CONFIG += qmltypes
QML_IMPORT_NAME = ProjectQmlComponents
QML_IMPORT_MAJOR_VERSION = 1

CONFIG *= file_copies # Since Qt 5.6, for more info see mkspecs/features/file_copies.prf
COPIES += APP_QML_TYPES
APP_QML_TYPES.files = $$OUT_PWD/$${TARGET}.qmltypes
APP_QML_TYPES.path = $$DESTDIR

This fragment generates makefile containing the following command:

qmltyperegistrar --generate-qmltypes=<my target in lower case>.qmltypes ...

which produces the issue if TARGET contains upper case letters. Actually, the issue comes from features/qmltypes.prf, line 32 (Qt 5.15.2):
TARGET_BASENAME = $$lower($$basename(TARGET))

Finally, due to TARGET mismatches due to letter's case there is "No rule to make target" error occurs further on make stage.

I would happy if features/qmltypes.prf will not mangle the initial TARGET name. Thanks!