Revert "build, qt: Do not install *.prl files"

This reverts commit 1155978d8f.

depends/packages/qt.mk

@@ -273,5 +273,5 @@ endef
 
 define $(package)_postprocess_cmds
   rm -rf native/mkspecs/ native/lib/ lib/cmake/ && \
-  rm -f lib/lib*.la
+  rm -f lib/lib*.la lib/*.prl plugins/*/*.prl
 endef

depends/patches/qt/qt.pro

@@ -3,10 +3,6 @@ cache(, super)
 
 !QTDIR_build: cache(CONFIG, add, $$list(QTDIR_build))
 
-prl = no_install_prl
-CONFIG += $$prl
-cache(CONFIG, add stash, prl)
-
 TEMPLATE = subdirs
 SUBDIRS = qtbase qttools qttranslations