profile: Support alternative profile.d locations

Typically Linux distributions employ /etc/profile.d for system wide
environment manipulation prior to multi-user initialisation. Modern
distribution efforts split the vendor configuration from the local
sysadmin configuration and data, by not using the /etc/ directories,
for example.

To enable this stateless pattern, this change adds a new --with-profile-dir
option to use an alternative location, such as within /usr/share/. This
ensures that the data (not configuration) is owned through the update
process, and does not conflict with changes made locally to the system,
enforcing domains of ownership.

To preserve backwards compatible behaviour, the default directory remains
set to /etc/profile.d.

Signed-off-by: Ikey Doherty <ikey@solus-project.com>

Makefile.am

@@ -119,7 +119,7 @@ completiondir = $(datadir)/bash-completion/completions
 completion_DATA = completion/flatpak
 EXTRA_DIST += $(completion_DATA)
 
-profiledir = $(sysconfdir)/profile.d
+profiledir = $(PROFILE_DIR)
 profile_DATA = flatpak.sh
 EXTRA_DIST += \
 	profile/flatpak.sh.in \

configure.ac

@@ -108,6 +108,12 @@ AC_ARG_WITH(system_fonts_dir,
 SYSTEM_FONTS_DIR=$with_system_fonts_dir
 AC_SUBST(SYSTEM_FONTS_DIR)
 
+AC_ARG_WITH(profile_dir,
+		AS_HELP_STRING([--with-profile-dir=PATH],[choose directory for profile.d files, [default=SYSCONFDIR/profile.d]]),
+            with_profile_dir="$withval", with_profile_dir=${sysconfdir}/profile.d)
+PROFILE_DIR=$with_profile_dir
+AC_SUBST(PROFILE_DIR)
+
 AC_ARG_VAR([BWRAP], [Bubblewrap executable])
 AC_ARG_WITH([system-bubblewrap],
             [AS_HELP_STRING([--with-system-bubblewrap], [Use system bwrap executable [default=check $BWRAP]])],