Fix 'libgomp.oacc-c/../libgomp.oacc-c-c++-common/acc_get_property-gcn.c' for C23 default

With commit 55e3bd37 "c: Default to -std=gnu23"
we've got:

    [-PASS:-]{+FAIL:+} libgomp.oacc-c/../libgomp.oacc-c-c++-common/acc_get_property-gcn.c -DACC_DEVICE_TYPE_radeon=1 -DACC_MEM_SHARED=0 -foffload=amdgcn-amdhsa  -O0  (test for excess errors)
    [-PASS:-]{+UNRESOLVED:+} libgomp.oacc-c/../libgomp.oacc-c-c++-common/acc_get_property-gcn.c -DACC_DEVICE_TYPE_radeon=1 -DACC_MEM_SHARED=0 -foffload=amdgcn-amdhsa  -O0  [-execution test-]{+compilation failed to produce executable+}
    [Etc.]

..., due to:

    [...]/libgomp.oacc-c/../libgomp.oacc-c-c++-common/acc_get_property-gcn.c:16:13: error: two or more data types in declaration specifiers
    [...]/libgomp.oacc-c/../libgomp.oacc-c-c++-common/acc_get_property-gcn.c:16:1: warning: useless type name in empty declaration

	libgomp/
	* testsuite/libgomp.oacc-c-c++-common/acc_get_property-gcn.c
	[!__cplusplus]: Don't 'typedef int bool;'.

libgomp/testsuite/libgomp.oacc-c-c++-common/acc_get_property-gcn.c

@@ -12,9 +12,6 @@
 #include <string.h>
 #include <openacc.h>
 
-#ifndef __cplusplus
-typedef int bool;
-#endif
 #include <hsa.h>