core: introduce seperate reverse dependencies for Requires= and Requisite=

This allows us to ensure that Requisite= dependencies never cause
propagation between units, while Requires= dependencies might.

http://lists.freedesktop.org/archives/systemd-devel/2015-May/031742.html

src/shared/unit-name.c

@@ -812,6 +812,8 @@ static const char* const unit_dependency_table[_UNIT_DEPENDENCY_MAX] = {
         [UNIT_PART_OF] = "PartOf",
         [UNIT_REQUIRED_BY] = "RequiredBy",
         [UNIT_REQUIRED_BY_OVERRIDABLE] = "RequiredByOverridable",
+        [UNIT_REQUISITE_OF] = "RequisiteOf",
+        [UNIT_REQUISITE_OF_OVERRIDABLE] = "RequisiteOfOverridable",
         [UNIT_WANTED_BY] = "WantedBy",
         [UNIT_BOUND_BY] = "BoundBy",
         [UNIT_CONSISTS_OF] = "ConsistsOf",

src/shared/unit-name.h

@@ -71,8 +71,10 @@ enum UnitDependency {
         UNIT_PART_OF,
 
         /* Inverse of the above */
-        UNIT_REQUIRED_BY,             /* inverse of 'requires' and 'requisite' is 'required_by' */
-        UNIT_REQUIRED_BY_OVERRIDABLE, /* inverse of 'requires_overridable' and 'requisite_overridable' is 'soft_required_by' */
+        UNIT_REQUIRED_BY,             /* inverse of 'requires' is 'required_by' */
+        UNIT_REQUIRED_BY_OVERRIDABLE, /* inverse of 'requires_overridable' is 'required_by_overridable' */
+        UNIT_REQUISITE_OF,            /* inverse of 'requisite' is 'requisite_of' */
+        UNIT_REQUISITE_OF_OVERRIDABLE,/* inverse of 'requisite_overridable' is 'requisite_of_overridable' */
         UNIT_WANTED_BY,               /* inverse of 'wants' */
         UNIT_BOUND_BY,                /* inverse of 'binds_to' */
         UNIT_CONSISTS_OF,             /* inverse of 'part_of' */