gitweb: Simplify (and fix) chop_str

gitweb: Simplify (and fix) chop_str

The chop_str subroutine is meant to be used on strings (such as commit
description / title) *before* HTML escaping, which means before
applying esc_html or equivalent.

Therefore get rid of the failed attempt to always remove full HTML
entities (like e.g. & or  ).  It is not necessary (HTML
entities gets added later), and it can cause chop_str to chop a string
incorrectly.

Specifically:

     API & protocol: support option to force written data immediately to disk

from http://git.kernel.org/?p=daemon/distsrv/chunkd.git;a=commit;h=3b02f749df2cb1288f345a689d85e7061f507e54

The short version of the title gets chopped to

     API ...

where it should be

     API & protocol: support option to force written data...

Noticed-by: John 'Warthog9' Hawley <redacted>
Signed-off-by: John 'Warthog9' Hawley <redacted>
Signed-off-by: Jakub Narebski <redacted>
Signed-off-by: Junio C Hamano <redacted>