bug#54671: 26.3; compilation mode tracking error messages

[Kenneth Zadeck]

There is a page on the web that purports to specify the format of error
messages for gnu products. I would have assumed that gnuemacs
would have fully implemented this set of standards.

https://www.gnu.org/prep/standards/html_node/Errors.html

The claim is that

"When an error is spread over several files, you can use this format:

file1:line1.column1-file2:line2.column2: message"

gnuemacs does not seem to understand this in the next error function.
It only sees the first file, line. The message

=====
../xmltools/XSD11/schemaDriver.xsd:10.1-../xmltools/XSD11/XMLSchema.xsd:86.1-../xmltools/XML/xml.xsd:4: 
Namespace 'http://www.w3.org/XML/1998/namespace' does not have access to 
items in namespace 'http://www.w3.org/2001/XMLSchema'.
=====
does not seem to trigger anything for the second and third file.
If this was a microsoft standard, i would understand and just suck it up,
but this is a gnu standard!!!!



In GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.14)
of 2020-03-26, modified by Debian built on lcy01-amd64-020
Windowing system distributor 'The X.Org Foundation