Make sure MUI2 UNBITMAP*_STRETCH have default values when using custom bitmaps


git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@6566 212acab6-be3b-0410-9dea-997c60f758d6
Fake the LPTSTR type if necessary for MakeNSIS on POSIX


git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@6567 212acab6-be3b-0410-9dea-997c60f758d6