[perl #128740] Check for null in pp_ghostent et al.

Specifically in the S_space_join_names_mortal static function that
several pp functions call.  On some platforms (such as Gentoo Linux
with torsocks), hent->h_aliases (where hent is a struct hostent *) may
be null after a gethostent call.

Author: Father Chrysostomos

embed.fnc

@@ -2119,7 +2119,7 @@ s	|OP*	|doform		|NN CV *cv|NN GV *gv|NULLOK OP *retop
 #  if !defined(HAS_MKDIR) || !defined(HAS_RMDIR)
 sR	|int	|dooneliner	|NN const char *cmd|NN const char *filename
 #  endif
-s	|SV *	|space_join_names_mortal|NN char *const *array
+s	|SV *	|space_join_names_mortal|NULLOK char *const *array
 #endif
 p	|OP *	|tied_method|NN SV *methname|NN SV **sp \
 				|NN SV *const sv|NN const MAGIC *const mg \

pp_sys.c

@@ -4931,9 +4931,7 @@ S_space_join_names_mortal(pTHX_ char *const *array)
 {
     SV *target;
 
-    PERL_ARGS_ASSERT_SPACE_JOIN_NAMES_MORTAL;
-
-    if (*array) {
+    if (array && *array) {
 	target = newSVpvs_flags("", SVs_TEMP);
 	while (1) {
 	    sv_catpv(target, *array);

proto.h

@@ -7037,11 +7037,7 @@ STATIC OP*	S_doform(pTHX_ CV *cv, GV *gv, OP *retop)
 #define PERL_ARGS_ASSERT_DOFORM	\
 	assert(cv); assert(gv)
 
-STATIC SV *	S_space_join_names_mortal(pTHX_ char *const *array)
-			__attribute__nonnull__(pTHX_1);
-#define PERL_ARGS_ASSERT_SPACE_JOIN_NAMES_MORTAL	\
-	assert(array)
-
+STATIC SV *	S_space_join_names_mortal(pTHX_ char *const *array);
 #endif
 #if defined(PERL_IN_REGCOMP_C)
 STATIC void	S__append_range_to_invlist(pTHX_ SV* const invlist, const UV start, const UV end)