[PATCH 2/2] allow_hipcc_tests: Allow native Windows (windows-msvc)

Make allow_hipcc_tests allow Windows as well.  Slightly tweak the
returned string to be more generic.  Add comment about why we do the
istarget check at all.

We only allow windows-msvc, and not mingw, as the AMD ROCm compiler on
Windows targets x86_64-pc-windows-msvc.

Change-Id: I45262f2fe24455ade6075eded2cd7df03979c6cc
---
 gdb/testsuite/lib/rocm.exp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/gdb/testsuite/lib/rocm.exp b/gdb/testsuite/lib/rocm.exp
index 025fa63da6f..439870b8263 100644
--- a/gdb/testsuite/lib/rocm.exp
+++ b/gdb/testsuite/lib/rocm.exp
@@ -138,8 +138,12 @@ gdb_caching_proc allow_hip_tests {} {
 	return {0 "remote debugging"}
     }
 
-    if {![istarget "*-linux*"]} {
-	return {0 "target platform is not Linux"}
+    # Check a hardcoded set of targets as an optimization, so that we
+    # save one external program invocation (of 'gdb --configuration')
+    # when GDB is not configured with amd-dbgapi support.  External
+    # program invocations have a non-negligible time cost on Windows.
+    if {![istarget "*-linux*"] && ![istarget "*-*-windows-msvc*"]} {
+	return {0 "target platform is not supported"}
     }
 
     # Ensure that GDB is built with amd-dbgapi support.
-- 
2.54.0