Add new module, locks_m, and add interfaces for prif_lock and

`prif_unlock`.

src/caffeine/locks_m.f90

@@ -0,0 +1,36 @@
+! Copyright (c), The Regents of the University of California
+! Terms of use are as specified in LICENSE.txt
+module locks_m
+  use iso_c_binding, only: c_intptr_t, c_int, c_bool
+
+  implicit none
+  private
+  public :: prif_lock_type, prif_lock, prif_unlock
+
+  type :: prif_lock_type
+  end type
+
+  interface
+
+     module subroutine prif_lock(image_num, lock_var_ptr, acquired_lock, stat, errmsg, errmsg_alloc)
+       implicit none
+       integer(c_int), intent(in) :: image_num
+       integer(c_intptr_t), intent(in) :: lock_var_ptr
+       logical(c_bool), intent(out), optional :: acquired_lock
+       integer(c_int), intent(out), optional :: stat
+       character(len=*), intent(inout), optional :: errmsg
+       character(len=:), intent(inout), allocatable, optional :: errmsg_alloc
+     end subroutine
+
+     module subroutine prif_unlock(image_num, lock_var_ptr, stat, errmsg, errmsg_alloc)
+       implicit none
+       integer(c_int), intent(in) :: image_num
+       integer(c_intptr_t), intent(in) :: lock_var_ptr
+       integer(c_int), intent(out), optional :: stat
+       character(len=*), intent(inout), optional :: errmsg
+       character(len=:), intent(inout), allocatable, optional :: errmsg_alloc
+     end subroutine
+
+  end interface
+
+end module locks_m

src/caffeine/locks_s.f90

@@ -0,0 +1,15 @@
+! Copyright (c), The Regents of the University of California
+! Terms of use are as specified in LICENSE.txt
+submodule(locks_m) locks_s
+
+  implicit none
+
+contains
+
+  module procedure prif_lock
+  end procedure
+
+  module procedure prif_unlock
+  end procedure
+
+end submodule locks_s

src/prif.f90

@@ -9,5 +9,6 @@ module prif
   use collective_subroutines_m, only : prif_co_sum, prif_co_max, prif_co_min, prif_co_reduce, prif_co_broadcast
   use teams_m, only: prif_form_team, prif_change_team, prif_end_team, prif_team_type
   use synchronization_m, only : prif_sync_all, prif_sync_images, prif_sync_team, prif_sync_memory
+  use locks_m, only: prif_lock_type, prif_lock, prif_unlock
   implicit none
 end module prif