modemmanager: add missing path for PID file

The procd based init setup uses a custom `pidfile` parameter, but the
used MODEMMANAGER_PID_FILE was not being defined anywhere.

Signed-off-by: Aleksander Morgado <aleksander@aleksander.es>

net/modemmanager/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=modemmanager
 PKG_VERSION:=1.10.8
-PKG_RELEASE:=5
+PKG_RELEASE:=6
 
 PKG_SOURCE:=ModemManager-$(PKG_VERSION).tar.xz
 PKG_SOURCE_URL:=https://www.freedesktop.org/software/ModemManager

net/modemmanager/files/modemmanager.common

@@ -11,6 +11,7 @@
 # Runtime state
 
 MODEMMANAGER_RUNDIR="/var/run/modemmanager"
+MODEMMANAGER_PID_FILE="${MODEMMANAGER_RUNDIR}/modemmanager.pid"
 MODEMMANAGER_CDCWDM_CACHE="${MODEMMANAGER_RUNDIR}/cdcwdm.cache"
 MODEMMANAGER_SYSFS_CACHE="${MODEMMANAGER_RUNDIR}/sysfs.cache"
 MODEMMANAGER_EVENTS_CACHE="${MODEMMANAGER_RUNDIR}/events.cache"