[systemd] Do not use script to launch buteo-mtp binary

The start-mtp.sh has a feature (create dummy directory for exposing parts of
user home directory via symlinks) that makes it look like it were a) meant
to be used for development time debugging, or b) some kind of attempt to
provide sandboxing.

While none of these features are needed in default setup, the ability to
control buteo-mtp environment from user editable files means they can be
activated without requiring any special prileges.

Launch buteo-mtp binary directly without involving launcher script.

To support things like controlling logging verbosity, add enablers for using
environment files in root writable directories.

Remove the now unused script altogether.

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

init/systemd/buteo-mtp.service

@@ -2,7 +2,9 @@
 Description=MTP service
 
 [Service]
-ExecStart=/usr/lib/mtp/start-mtp.sh
+EnvironmentFile=-/etc/sysconfig/buteo-mtp
+EnvironmentFile=-/var/lib/environment/buteo-mtp/*.conf
+ExecStart=/usr/lib/mtp/mtp_service $SERVICE_PARAMETERS
 Restart=always
 RestartSec=1
 Nice=-10

service/service.pro

@@ -17,7 +17,7 @@ SOURCES += service.cpp
 
 #install
 target.path += /usr/lib/mtp/
-target.files = start-mtp.sh mtp_service
+target.files = mtp_service
 desktop.path = /etc/xdg/autostart
 desktop.files = buteo-mtp.desktop
 INSTALLS += target desktop