[OpenACC] Set 'acc_device_current = -1'

There's no point in using value '-3', and even though not directly related,
value '-1' does match 'GOMP_DEVICE_ICV'.

	libgomp/
	* config/accel/openacc.f90 (acc_device_current): Set to '-1'.
	* openacc.f90 (acc_device_current): Likewise.
	* openacc.h (acc_device_current): Likewise.
	* openacc_lib.h (acc_device_current): Likewise.

libgomp/ChangeLog

 2020-04-29  Thomas Schwinge  <thomas@codesourcery.com>
 
+	* config/accel/openacc.f90 (acc_device_current): Set to '-1'.
+	* openacc.f90 (acc_device_current): Likewise.
+	* openacc.h (acc_device_current): Likewise.
+	* openacc_lib.h (acc_device_current): Likewise.
+
 	PR target/94282
 	* testsuite/libgomp.c-c++-common/function-not-offloaded.c: Remove
 	'dg-allow-blank-lines-in-output'.

libgomp/config/accel/openacc.f90

@@ -44,7 +44,7 @@ module openacc_kinds
   integer, parameter :: acc_device_kind = int32
 
   ! Keep in sync with include/gomp-constants.h.
-  integer (acc_device_kind), parameter :: acc_device_current = -3
+  integer (acc_device_kind), parameter :: acc_device_current = -1
   integer (acc_device_kind), parameter :: acc_device_none = 0
   integer (acc_device_kind), parameter :: acc_device_default = 1
   integer (acc_device_kind), parameter :: acc_device_host = 2

libgomp/openacc.f90

@@ -41,7 +41,7 @@ module openacc_kinds
   integer, parameter :: acc_device_kind = int32
 
   ! Keep in sync with include/gomp-constants.h.
-  integer (acc_device_kind), parameter :: acc_device_current = -3
+  integer (acc_device_kind), parameter :: acc_device_current = -1
   integer (acc_device_kind), parameter :: acc_device_none = 0
   integer (acc_device_kind), parameter :: acc_device_default = 1
   integer (acc_device_kind), parameter :: acc_device_host = 2

libgomp/openacc.h

@@ -49,7 +49,7 @@ extern "C" {
 /* Types */
 typedef enum acc_device_t {
   /* Keep in sync with include/gomp-constants.h.  */
-  acc_device_current = -3,
+  acc_device_current = -1,
   acc_device_none = 0,
   acc_device_default = 1,
   acc_device_host = 2,

libgomp/openacc_lib.h

@@ -37,7 +37,7 @@
       integer, parameter :: acc_device_kind = 4
 
 !     Keep in sync with include/gomp-constants.h.
-      integer (acc_device_kind), parameter :: acc_device_current = -3
+      integer (acc_device_kind), parameter :: acc_device_current = -1
       integer (acc_device_kind), parameter :: acc_device_none = 0
       integer (acc_device_kind), parameter :: acc_device_default = 1
       integer (acc_device_kind), parameter :: acc_device_host = 2