Issues in Makefile files

[D3vil0p3r]

The Makefile files in the project have some missing logic:

• uninstall is exiting with error if the user uninstalls the application when systemd service is not running. Please, insert a condition to stop it only if it is running.
• DESTDIR is added but missing on the needed code
• egrep in src/libmerc/Makefile.in should be replaced by grep -E because deprecated (and to prevent annoying warning messages.

The 2nd bullet is a blocking one. The building from source works if the user does not specify DESTDIR. If it is specified, sudo make DESTDIR=anyfolder install process does not work properly because it still installs the application in the system root tree. On a fakeroot environment, instead, produces an error. So, it occurs mostly for those users that would install the application in a different path or in fakeroot (i.e., for packaging reasons).

Repro steps:

git clone https://github.com/cisco/mercury --recursive

cd mercury
mkdir proof
./configure
make
sudo make DESTDIR=./proof install

but it does not install anything in ./proof directory because Makefile and src/Makefile.in (not sure if other Makefile.in files in the repo are affected) still refer to the system root tree.

@banderson84 @andrewchi can you give a look to it please? Furthermore, can you please, in the README, to explicitly indicate which are the dependencies only for building process and the ones needed for runtime?