tmac/tmac.an: define .MR in a groff compatible way

groff 1.23.0 added .MR to its -man macro package.  The NEWS file states
that the inclusion of the macro "was prompted by its introduction to
Plan 9 from User Space's troff in August 2020."  From d32deab it seems
that the name for Plan 9 from User Space's implementation was suggested
by groff maintainer G. Brandon Robinson.

Not sure if the intention was to make these definitions compatible, but
it would be nice if they were.

Currently, Plan 9 from User Space's .MR expects its second argument to
be parenthesized.  groff's .MR does not.  This results in extra
parentheses appearing in manual references when viewing Plan 9 from User
Space's manual pages on a system using groff.

1 files changed, 5 insertions, 5 deletions

diff --git a/man/man3/ndb.3 b/man/man3/ndb.3
index 413c11d6..f9c37f92 100644
--- a/man/man3/ndb.3
+++ b/man/man3/ndb.3
@@ -88,13 +88,13 @@ Ndbtuple*	ndbsubstitute(Ndbtuple *t, Ndbtuple *from, Ndbtuple *to);
 These routines are used by network administrative programs to search
 the network database.
 They operate on the database files described in
-.MR ndb (7) .
+.MR ndb 7 .
 .PP
 .I Ndbopen
 opens the database
 .I file
 and calls
-.MR malloc (3)
+.MR malloc 3
 to allocate a buffer for it.
 If
 .I file
@@ -128,7 +128,7 @@ is used to find each successive match.
 On a successful search both return a linked list of
 .I Ndbtuple
 structures acquired by
-.MR malloc (3)
+.MR malloc 3
 that represent the attribute/value pairs in the
 entry.
 On failure they return zero.
@@ -450,8 +450,8 @@ directory of network database files
 .SH SOURCE
 .B \*9/src/libndb
 .SH SEE ALSO
-.MR ndb (1)
-.MR ndb (7)
+.MR ndb 1
+.MR ndb 7
 .SH DIAGNOSTICS
 .IR Ndbgetvalue
 and