test-stack-traces: relax parsing rules

 * accept forward and backward slashes in file paths
 * strip multiple extensions; e.g. if the basename is "test.exe.obj"
   then it strips to "test".

Author: andrewrk

test/tests.zig

@@ -923,7 +923,7 @@ pub const StackTracesContext = struct {
                         pos = marks[i] + delim.len;
                     }
                     // locate source basename
-                    pos = mem.lastIndexOfScalar(u8, line[0..marks[0]], fs.path.sep) orelse {
+                    pos = mem.lastIndexOfAny(u8, line[0..marks[0]], "\\/") orelse {
                         // unexpected pattern: emit raw line and cont
                         try buf.appendSlice(line);
                         try buf.appendSlice("\n");
@@ -935,9 +935,9 @@ pub const StackTracesContext = struct {
                     try buf.appendSlice(line[pos + 1 .. marks[2] + delims[2].len]);
                     try buf.appendSlice(" [address]");
                     if (self.mode == .Debug) {
-                        if (mem.lastIndexOfScalar(u8, line[marks[4]..marks[5]], '.')) |idot| {
-                            // On certain platforms (windows) or possibly depending on how we choose to link main
-                            // the object file extension may be present so we simply strip any extension.
+                        // On certain platforms (windows) or possibly depending on how we choose to link main
+                        // the object file extension may be present so we simply strip any extension.
+                        if (mem.indexOfScalar(u8, line[marks[4]..marks[5]], '.')) |idot| {
                             try buf.appendSlice(line[marks[3] .. marks[4] + idot]);
                             try buf.appendSlice(line[marks[5]..]);
                         } else {