tests: omit -p for external diff via extdiff extension for portability Before this patch, some tests using external "diff" command via extdiff extension fail on Solaris, because "-p" (show which C function each change is in) option isn't supported by system standard "diff" on Solaris, even though extdiff passes it to external "diff" by default. Fortunately, this non-portable option isn't important for (current, at least) tests using external "diff" command via extdiff extension. This patch omits "-p" for external "diff" command via extdiff extension for portability of tests, and adds check-code.py a rule to detect invocation of "diff" with "-p". Newly added check-code.py rule examines only lines generated by external "diff" with "-r", because strict examination might misidentify "hg diff -p" or other complicated lines consisting of "diff" string as wrong one. This patch is a part of making tests using external "diff" portable, and tests below aren't yet portable even after this patch. test-graft.t test-largefiles-update.t test-subrepo-deep-nested-change.t

running: init test1
result: None
running: add foo
result: 0
running: commit -m commit1 -d 2000-01-01 foo
result: None
running: commit -m commit2 -d 2000-01-02 foo
result: None
running: log -r 0
changeset:   0:0e4634943879
user:        test
date:        Sat Jan 01 00:00:00 2000 +0000
summary:     commit1

result: None
running: log -r tip
changeset:   1:45589e459b2e
tag:         tip
user:        test
date:        Sun Jan 02 00:00:00 2000 +0000
summary:     commit2

result: None