CPack/RPM: fix error message associated with source path length
The shorter and longer aspects of this message where interchanged.
for example:
Make Error at /usr/local/cmake-3.8.20170323-g82db83-Linux-x86_64/share/cmake-3.8/Modules/CPackRPM.cmake:1484 (message):
CPackRPM: source dir path '/usr/src/m' is longer than debuginfo sources dir
path '/usr/src/debug/MariaDB-5.5.55-fedora-x86_64/client/src_0'! Source dir
path must be shorter than debuginfo sources dir path. Set
CPACK_RPM_BUILD_SOURCE_DIRS_PREFIX variable to a shorter value or make
source dir path longer. Required for debuginfo packaging. See
documentation of CPACK_RPM_DEBUGINFO_PACKAGE variable for details.
Topic-rename: cpack-rpm-correct-error-message-debug-lengths