bison-generated code causes compilation failure on OpenBSD 4.7

[Jim Meyering]

Hello,

On an OpenBSD 4.7 system, building coreutils fails like this:
(noticed in prerelease testing)

  make[2]: Entering directory `/u/guest/meyering/coreutils-8.5.185-0ad44/lib'
    CC       parse-datetime.o
    parse-datetime.c:590: error: conflicting types for 'malloc'

The problematic code is from bison's skeleton:

#  ifndef YYMALLOC
#   define YYMALLOC malloc
#   if ! defined malloc && ! defined _STDLIB_H && (defined __STDC__ || defined 
__C99__FUNC__ \
     || defined __cplusplus || defined _MSC_VER)
void *malloc (YYSIZE_T); /* INFRINGES ON USER NAME SPACE */

There are two problems.
First, YYSIZE_T is defined to __SIZE_TYPE__, which is defined
to "unsigned int" (don't recall where).
That obviously fails to match the expected "size_t".

Stepping back, malloc shouldn't even be declared here, since
this skeleton code has already included stdlib.h.
The code above attempts to detect that by testing for _STDLIB_H,
but on this system, that symbol is not defined.
Instead, OpenBSD's stdlib.h spells it as _STDLIB_H_, with
the added trailing underscore.

When I change the above to this, it solves the problem:

#  ifndef YYMALLOC
#   define YYMALLOC malloc
#   if ! defined malloc && ! defined _STDLIB_H && ! defined _STDLIB_H_ \
     && (defined __STDC__ || defined __C99__FUNC__ \
     || defined __cplusplus || defined _MSC_VER)
void *malloc (YYSIZE_T); /* INFRINGES ON USER NAME SPACE */

However, if you like this approach I'm sure you'll want to
change some of the other uses of _STDLIB_H.

FYI, I regenerated parse-datetime.c with the latest from bison.git's
master branch, and it's the same.