Leave paths containing '/~' alone

We do not perform tilde expansion in the MSys2 runtime; let's leave
those paths intact for programs that want to expand such paths
themselves.

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

winsup/cygwin/msys2_path_conv.cc

@@ -364,6 +364,10 @@ path_type find_path_start_and_type(const char** src, int recurse, const char* en
         case '[':
         case ']':
             goto skip_p2w;
+        case '/':
+            if (it + 1 < end && it[1] == '~')
+                goto skip_p2w;
+            break;
         ++it;
     }
     it = *src;