Throughout, change fdtab references to cygheap->fdtab.

* child_info.h (cygheap_exec_info): Eliminate special fdtab stuff.
* spawn.cc (spawn_guts): Ditto.
* cygheap.cc (cygheap_init): Initialize fdtab, if appropriate.
* cygheap.h (CYGHEAPSIZE): Include size of init_cygheap.
(_cmalloc_entry): Include fdtab here.
* dtable.h (dtable): Declare/define new methods.
* dtable.cc (dtable::vfork_child_fixup): New method.
(dtable::fixup_after_exec): Remove unneeded extra arguments.
* dcrt0.cc (dll_crt0_1): Ditto.
* environ.cc (getwinenv): Use case sensitive comparison.
(winenv): Make a copy of environment cache to avoid realloc problems when
duplicate environment variables exist in the environment.  (From Egor Duda)
* net.cc (cygwin_socket): Revert Apr 14 change.
* include/sys/file.h: Protect against previous X_OK definition.
* passwd.cc: Eliminate passwd_sem throughout.
* security.cc: Ditto.
* cygwin.din: Export New functions.
* passwd.cc (read_etc_passwd): Make race safe.
(getpwuid_r): New function.
(getpwnam_r): New function.

winsup/cygwin/sysconf.cc

@@ -16,6 +16,7 @@ details. */
 #include <ntdef.h>
 #include "fhandler.h"
 #include "dtable.h"
+#include "cygheap.h"
 #include "cygerrno.h"
 #include "ntdll.h"
 
@@ -34,7 +35,7 @@ sysconf (int in)
 	/* FIXME: this returns the current limit which can increase
 	   if and when dtable::find_unused_handle is called.  Perhaps
 	   we should return NOFILE or OPEN_MAX instead? */
-	return fdtab.size;
+	return cygheap->fdtab.size;
       case _SC_PAGESIZE:
 	return getpagesize ();
       case _SC_CLK_TCK: