debian: install dashed commands to /usr/libexec instead of /usr/lib
lintian explains:
Debian adopted the Filesystem Hierarchy Specification (FHS) version
3.0 starting with our policy revision 4.1.5. The FHS 3.0 describes
/usr/libexec. Please use that location for executables.
The FHS states
Some previous versions of this document did not support /usr/libexec,
despite it being standard practice in a number of environments.
To accomodate this restriction, it became common practice to use
/usr/lib instead. Either practice is now acceptable, but each
application must choose one way or the other to organize itself.
Using /usr/libexec separates them from the libraries in /usr/lib and
matches the defaults in the upstream Makefile a little better.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>