Support interactive commands in standard MINGW as well (#2243)

* Support interactive commands in standard MINGW as well

Previous fix only supported some old configuration of Git bash
provided by Git for windows, newer Git bash use standard MINGW
which uses a different `uname` but the fix is ultimately the same

Github: #743

* Refactor: use better variable name when determine to use winpty

* Support both MSYS 32bit and 64bit terminal emulators

bin/yarn

@@ -1,19 +1,19 @@
 #!/bin/sh
 basedir=$(dirname "$(readlink "$0" || echo "$(echo "$0" | sed -e 's,\\,/,g')")")
 
-is_msys=0
+use_winpty=0
 
 case `uname` in
   *CYGWIN*) basedir=`cygpath -w "$basedir"`;;
-  *MSYS_NT*) is_msys=1;;
+  MSYS*|MINGW*) use_winpty=1;;
 esac
 
 command_exists() {
   command -v "$1" >/dev/null 2>&1;
 }
 
 if command_exists node; then
-  if [ $is_msys -eq 1 ]; then
+  if [ $use_winpty -eq 1 ]; then
     winpty node "$basedir/yarn.js" "$@"
   else
     node "$basedir/yarn.js" "$@"