qtbase: remove absolute binary paths from mkspec files

When running 'bitbake -c populate_sdk' on an image that has qt5webkit
enabled, the uikit feature is enabled in qtbase, which then fails to install
with

  error: qtbase-mkspecs-5.8.0+git0+49dc9aa409-r0 conflicts with /usr/bin/perl

The culprit for this is /usr/lib/qt5/mkspecs/features/uikit/devices.pl,
which has #!/usr/bin/perl hardcoded. Fix this in a similar way other recipes
do it as well and strip out these bits at install time.

Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

recipes-qt/qt5/qtbase_git.bb

@@ -178,6 +178,10 @@ do_install_append() {
     sed -i -e 's|${STAGING_DIR_NATIVE}${prefix_native}|$$[QT_HOST_PREFIX/get]|g' \
         -e 's|${STAGING_DIR_HOST}|$$[QT_SYSROOT]|g' \
         ${D}/${OE_QMAKE_PATH_QT_ARCHDATA}/mkspecs/*.pri
+
+    # Fix up absolute paths in scripts
+    grep -lr /usr/bin/perl ${D}${OE_QMAKE_PATH_QT_ARCHDATA}/ | \
+        xargs -r sed -i -e '1s,#!.*perl,#! ${USRBINPATH}/env perl,'
 }
 
 # mkspecs have mac specific scripts that depend on perl and bash