windows: Fixed MSYS detection in CCCL.

Fixed a path mapping problem (slash replaced by path) with current msys versions.

cccl assumes that MACHTYPE contains "-msys" on msys and then configures slashes to
'-' to avoid path mapping problems with slashes. However, at least in the current
MSYS version, MACHTYPE reports as cygwin. A better way to detect MSYS is to use
the MSYSTEM variable.
I'm assuming that this check has been failing for a while, but not causing cccl
to fail, but in current MSYS versions the path mapping logic has changed.

See also swig/cccl#20

Signed-off-by: Frank Wagner <frank.wagner@dbosoft.eu>
Acked-by: Mike Pattrick <mkp@redhat.com>
Signed-off-by: Alin Gabriel Serdean <aserdean@ovn.org>

Author: dbosoft-fw

build-aux/cccl

@@ -33,14 +33,22 @@ EOF
     exit $1
 }
 
-case $MACHTYPE in
-    *-msys)
-        slash="-"
-        ;;
-    *)
-        slash="/"
-        ;;
-esac
+
+
+# Check for MSYS which now reports itself as cygwin in MACHTYPE
+if [[ -n "$MSYSTEM" ]]; then
+    slash="-"
+else
+    # fallback to old behavior
+    case $MACHTYPE in
+        *-msys)
+            slash="-"
+            ;;
+        *)
+            slash="/"
+            ;;
+    esac
+fi
 # prog specifies the program that should be run (cl.exe or link.exe)
 # We'll assume cl to start out
 prog=cl