gh: allow running in WSL

In WSL, we do not have `/usr/bin/winpty`. Let's verify that it is
available before using it, falling back to the `winpty`-less invocation.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

mingw-w64-github-cli/PKGBUILD

@@ -20,7 +20,7 @@ source=("$_realname-$pkgver.tar.gz::$url/archive/v$pkgver.tar.gz"
         "gh")
 sha256sums=('5bdbc589a6d5cca241b2dc467d846a8f23c465d78efd898271f18b636608d6e6'
             '4377ead0f9db015c0f290a8b86fbb630939a668622dd69ec882626aa8615e662'
-            '205b991248cd57c594f3be2cc1af9ea4a1a34c6008a16fac55ff8c49a4d664f8')
+            '9ee5f2b44b7e9aa751508f02c1020e341e0212a9aa146b7428eb5ffea310be27')
 prepare() {
   cd "cli-$pkgver"
   patch -p1 -i ${srcdir}/0001-makefile-add-exe.patch

mingw-w64-github-cli/gh

@@ -2,7 +2,7 @@
 
 GH_EXE="$( dirname ${BASH_SOURCE[0]} )/gh.exe"
 
-if [ -t 0 -a -t 1 ]; then
+if [ -t 0 -a -t 1 -a -x /usr/bin/winpty ]; then
   /usr/bin/winpty $GH_EXE "$@"
 else
   exec $GH_EXE "$@"