Don't include sys/param.h

sys/param.h on recent versions of powerpc glibc ends up including
asm/elf.h via asm/sigcontex.h.  asm/elf.h defines R_PPC_* and R_PPC64_*
macros, which clash with our include/elf/ppc.h and include/elf/ppc64.h.
It turns out that no current source uses LD_PATHMAX, so there is no
need for limits.h or sys/param.h, except for one occurrence of UINT_MAX.
I don't have a quarrel with limits.h, but it seems unnecessary just
for UINT_MAX.

	* sysdep.h: Don't include limits.h and sys/param.h.  Don't
	include unistd.h twice.
	(LD_PATHMAX): Don't define.
	* ldlang.c (lang_common): Don't use UINT_MAX.

ld/sysdep.h

@@ -56,34 +56,12 @@ extern char *strrchr ();
 #include <unistd.h>
 #endif
 
-/* for PATH_MAX */
-#ifdef HAVE_LIMITS_H
-#include <limits.h>
-#endif
-/* for MAXPATHLEN */
-#ifdef HAVE_SYS_PARAM_H
-#include <sys/param.h>
-#endif
-#ifdef PATH_MAX
-# define LD_PATHMAX PATH_MAX
-#else
-# ifdef MAXPATHLEN
-#  define LD_PATHMAX MAXPATHLEN
-# else
-#  define LD_PATHMAX 1024
-# endif
-#endif
-
 #ifdef HAVE_REALPATH
 # define REALPATH(a,b) realpath (a, b)
 #else
 # define REALPATH(a,b) NULL
 #endif
 
-#ifdef HAVE_UNISTD_H
-#include <unistd.h>
-#endif
-
 #ifdef USE_BINARY_FOPEN
 #include "fopen-bin.h"
 #else