Support testing for builtin Lua with a macro conditional

Only define builtin %{lua:...} if actually compiled with the support.
This loses the "informative" error message about the situation but
I think ability to test feature presence is more useful and important.

rpmio/macro.c

@@ -1005,9 +1005,9 @@ static void doOutput(MacroBuf mb,  rpmMacroEntry me, const char * g, size_t gn)
     _free(buf);
 }
 
+#ifdef WITH_LUA
 static void doLua(MacroBuf mb,  rpmMacroEntry me, const char * g, size_t gn)
 {
-#ifdef WITH_LUA
     rpmlua lua = NULL; /* Global state. */
     char *scriptbuf = xmalloc(gn + 1);
     char *printbuf;
@@ -1042,10 +1042,8 @@ static void doLua(MacroBuf mb,  rpmMacroEntry me, const char * g, size_t gn)
 	free(printbuf);
     }
     free(scriptbuf);
-#else
-    mbErr(mb, 1, _("<lua> scriptlet support not built in\n"));
-#endif
 }
+#endif
 
 static void
 doSP(MacroBuf mb, rpmMacroEntry me, const char * g, size_t gn)
@@ -1267,7 +1265,9 @@ static struct builtins_s {
     { "getncpus",	doFoo,		ME_FUNC },
     { "global",		doGlobal,	ME_PARSE },
     { "load",		doLoad,		ME_ARGFUNC },
+#ifdef WITH_LUA
     { "lua",		doLua,		ME_ARGFUNC },
+#endif
     { "macrobody",	doBody,		ME_ARGFUNC },
     { "quote",		doFoo,		ME_ARGFUNC },
     { "shrink",		doFoo,		ME_ARGFUNC },

tests/rpmmacro.at

@@ -526,6 +526,16 @@ runroot rpm \
 [])
 AT_CLEANUP
 
+AT_SETUP([test lua support])
+AT_KEYWORDS([macros lua])
+AT_CHECK([[
+lua_disabled=$(runroot rpm --eval '%[%{defined lua}?"0":"1"]'|tr -d '\n')
+test $lua_disabled = $LUA_DISABLED
+]],
+[1],
+[])
+AT_CLEANUP
+
 AT_SETUP([simple lua --eval])
 AT_KEYWORDS([macros lua])
 AT_CHECK([