Implement appending to standard man(7) and mdoc(7) macros with .am.

With roff_getstrn(), provide finer control which definitions
can be used for what:
* All definitions can be used for .if d tests and .am appending.
* User-defined for \* expansion, .dei expansion, and macro calling.
* Predefined for \* expansion.
* Standard macros, original or renamed, for macro calling.

Several related improvements while here:
* Do not return string table entries that have explicitly been removed.
* Do not create a rentab entry when trying to rename a non-existent macro.
* Clear an existing rentab entry when the external interface
roff_setstr() is called with its name.
* Avoid trailing blanks in macro lines generated from renamed
and from aliased macros.
* Delete the duplicate __m*_reserved[] tables, just use roff_name[].

1 files changed, 7 insertions, 3 deletions

diff --git a/regress/roff/string/Makefile b/regress/roff/string/Makefile
index d2cd125b..354a7a75 100644
--- a/regress/roff/string/Makefile
+++ b/regress/roff/string/Makefile
@@ -1,11 +1,15 @@
 # $OpenBSD: Makefile,v 1.6 2014/07/06 19:08:57 schwarze Exp $
 
-REGRESS_TARGETS=escape infinite zerolength name
-LINT_TARGETS = name
+REGRESS_TARGETS	 = escape infinite name std zerolength
+LINT_TARGETS	 = name std
 
 # The infinite test fails badly with groff-1.20.1:
 # It fails to print the following text.
 
-SKIP_GROFF ?= infinite
+SKIP_GROFF	?= infinite
+
+# Groff can expand standard macros as strings, but mandoc cannot.
+
+SKIP_GROFF	+= std
 
 .include <bsd.regress.mk>