Fix the creation of the checkXML script.

This partially resolves bug report 694.

kdoctools/checkXML.cmake

@@ -3,5 +3,5 @@
 prefix=@CMAKE_INSTALL_PREFIX@
 # FIXME this must be separate?
 exec_prefix=@CMAKE_INSTALL_PREFIX@
-exit `@CMAKE_INSTALL_PREFIX@/@BIN_INSTALL_DIR@/meinproc --check --stdout $@ > /dev/null`
+exit `@BIN_INSTALL_DIR@/meinproc --check --stdout $@ > /dev/null`