x/build: Add gdb to Windows Builders

[johnsonj]

As observed in #22012 the Windows builders do not have gdb causing them to skip any gdb related test.

Add gdb to these packages

[alexbrainman]

@johnsonj while you at it ...

2 out of 5 gdb tests are skipped on my computer:

c:\Users\Alex\dev\go\src>go test -v -run=TestGdb runtime
=== RUN   TestGdbPython
=== RUN   TestGdbPythonCgo
=== RUN   TestGdbBacktrace
=== RUN   TestGdbAutotmpTypes
=== RUN   TestGdbConst
--- SKIP: TestGdbPython (0.05s)
        runtime-gdb_test.go:55: gdb version 7.8
        runtime-gdb_test.go:70: skipping due to lack of python gdb support: Python scripting is not supported in this copy of GDB.
--- SKIP: TestGdbPythonCgo (0.04s)
        runtime-gdb_test.go:55: gdb version 7.8
        runtime-gdb_test.go:70: skipping due to lack of python gdb support: Python scripting is not supported in this copy of GDB.
--- PASS: TestGdbBacktrace (0.51s)
        runtime-gdb_test.go:55: gdb version 7.8
--- PASS: TestGdbAutotmpTypes (0.54s)
        runtime-gdb_test.go:55: gdb version 7.8
--- PASS: TestGdbConst (0.54s)
        runtime-gdb_test.go:55: gdb version 7.8
        runtime-gdb_test.go:436: output "No symbol \"startup\" in current context.\nBreakpoint 1 at 0x44d004: file C:/Users/Alex/AppData/Local/Temp/go-build263992595/main.go, line 9.\n[New Thread 6644.0x2228]\n[New Thread 6644.0x6a8]\n[New Thread 6644.0x2938]\n[New Thread 6644.0x135c]\nwarning: Can not parse XML library list; XML support was disabled at compile time\n[New Thread 6644.0x1dd4]\n[New Thread 6644.0x2258]\n[New Thread 6644.0x239c]\n[New Thread 6644.0x1a9c]\n\nBreakpoint 1, main.main () at C:/Users/Alex/AppData/Local/Temp/go-build263992595/main.go:9\n9\t\tprintln(\"hello world\")\n$1 = 42\n$2 = 18446744073709551615\n$3 = -1\n$4 = 1 '\\001'\n"
PASS
ok      runtime 0.649s

c:\Users\Alex\dev\go\src>

I suspect it would be hard to make skipped tests run. As far as I remember I tried some time ago and failed. Do not spent too much time on it if you cannot.

Alex

[alexbrainman]

@johnsonj when selecting what gdb version to run, just be aware that gdb 7.9.1 fails with our tests - see #24743 for details.

Alex