ffix: add space between function and () if BR or IR

Detected through the regex:
	git grep -P '^\.(BR|IR) [\w]*\([\d]*\)$'

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man3/getgrent.3

@@ -155,13 +155,13 @@ local group database file
 .SH ATTRIBUTES
 .SS Multithreading (see pthreads(7))
 The
-.BR getgrent()
+.BR getgrent ()
 function is not thread-safe.
 .LP
 The
-.BR setgrent()
+.BR setgrent ()
 and
-.BR endgrent()
+.BR endgrent ()
 functions are thread-safe.
 .SH CONFORMING TO
 SVr4, 4.3BSD, POSIX.1-2001.

man3/getpwent.3

@@ -154,13 +154,13 @@ local password database file
 .SH ATTRIBUTES
 .SS Multithreading (see pthreads(7))
 The
-.BR getpwent()
+.BR getpwent ()
 function is not thread-safe.
 .LP
 The
-.BR setpwent()
+.BR setpwent ()
 and
-.BR endpwent()
+.BR endpwent ()
 functions are thread-safe.
 .SH CONFORMING TO
 SVr4, 4.3BSD, POSIX.1-2001.

man7/socket.7

@@ -452,7 +452,7 @@ For more information see
 This option, which is currently supported only for
 .BR unix (7)
 sockets, sets the value of the "peek offset" for the
-.BR recv(2)
+.BR recv (2)
 system call when used with
 .BR MSG_PEEK
 flag.
@@ -460,7 +460,7 @@ flag.
 When this option is set to a negative value
 (it is set to \-1 for all new sockets),
 traditional behavior is provided:
-.BR recv(2)
+.BR recv (2)
 with the
 .BR MSG_PEEK
 flag will peek data from the front of the queue.