Year 2000 fixes for groff

PR:		4930
Submitted by:	Stephen J. Roznowski

contrib/groff/tmac/doc-common

@@ -266,7 +266,7 @@
 .		if "\\n(mo"10" .ds dD October
 .		if "\\n(mo"11" .ds dD November
 .		if "\\n(mo"12" .ds dD December
-.		as dD \&\ \\n(dy, 19\\n(yr
+.		as dD \&\ \\n(dy, \\n(yr+1900
 .	\}
 .\}
 .el \{\

contrib/groff/tmac/tmac.e

@@ -1519,7 +1519,7 @@ in \\f2\\*([B\\f1, \c
 .if \n(dw=5 .ds dw Thursday
 .if \n(dw=6 .ds dw Friday
 .if \n(dw=7 .ds dw Saturday
-.ds td \*(mo \n(dy, 19\n(yr
+.ds td \*(mo \n(dy, \n(yr+1900
 .\"		*** PARAMETRIC INITIALIZATIONS ***
 .rr x
 .nr $v \n(.v00+\n(.sp-1/\n(.sp	\" vs as percentage of ps for .sz request