runtime: increase GDB version testing requirement to 10 from 7.7

Bump the required version of GDB up to 10 from 7.7 in the runtime GDB
tests, so as to ensure that we have something that can handle DWARF 5
when running tests. In theory there is some DWARF 5 support on the
version 9 release branch, but we get "Dwarf Error: DW_FORM_addrx"
errors for some archs on builders where GDB 9.2 is installed.

Updates #26379.

Change-Id: I1b7b45f8e4dd1fafccf22f2dda0124458ecf7cba
Reviewed-on: https://go-review.googlesource.com/c/go/+/656836
Auto-Submit: Ian Lance Taylor <[email protected]>
Reviewed-by: David Chase <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: thanm

src/runtime/runtime-gdb_test.go

@@ -73,7 +73,9 @@ func checkGdbVersion(t *testing.T) {
 	if err1 != nil || err2 != nil {
 		t.Skipf("skipping: can't determine gdb version: %v, %v", err1, err2)
 	}
-	if major < 7 || (major == 7 && minor < 7) {
+	// The Go toolchain now generates DWARF 5 by default, which needs
+	// a GDB version of 10 or above.
+	if major < 10 {
 		t.Skipf("skipping: gdb version %d.%d too old", major, minor)
 	}
 	t.Logf("gdb version %d.%d", major, minor)