Remove special logic for the obscure CMU C library's libc.h

* acinclude.m4 (GUILE_HEADER_LIBC_WITH_UNISTD): removed
* configure.ac: remove GUILE_HEADER_LIBC_WITH_UNISTD, don't check for libc.h
* libguile/filesys.c [LIBC_H_WITH_UNISTD_H]: remove libc.h inclusion
* libguile/posix.c [LIBC_H_WITH_UNISTD_H]: remove libc.h inclusion

acinclude.m4

@@ -44,51 +44,6 @@ struct utime blah;
   fi])
 
 
-
-
-dnl
-dnl Apparently, at CMU they have a weird version of libc.h that is
-dnl installed in /usr/local/include and conflicts with unistd.h.
-dnl In these situations, we should not #include libc.h.
-dnl This test arranges to #define LIBC_H_WITH_UNISTD_H iff libc.h is
-dnl present on the system, and is safe to #include.
-dnl
-AC_DEFUN([GUILE_HEADER_LIBC_WITH_UNISTD],
-  [
-    AC_CHECK_HEADERS(libc.h unistd.h)
-    AC_CACHE_CHECK(
-      [whether libc.h and unistd.h can be included together],
-      guile_cv_header_libc_with_unistd,
-      [
-        if test "$ac_cv_header_libc_h" = "no"; then
-          guile_cv_header_libc_with_unistd="no"
-        elif test "$ac_cv_header_unistd_h" = "no"; then
-          guile_cv_header_libc_with_unistd="yes"
-        else
-          AC_TRY_COMPILE(
-	    [
-#             include <libc.h>
-#             include <unistd.h>
-	    ],
-	    [],
-	    [guile_cv_header_libc_with_unistd=yes],
-	    [guile_cv_header_libc_with_unistd=no]
-          )
-        fi
-      ]
-    )
-    if test "$guile_cv_header_libc_with_unistd" = yes; then
-      AC_DEFINE([LIBC_H_WITH_UNISTD_H], 1,
-        [Define this if we should include <libc.h> when we've already
-         included <unistd.h>.  On some systems, they conflict, and libc.h
-         should be omitted.  See GUILE_HEADER_LIBC_WITH_UNISTD in
-         aclocal.m4.])
-    fi
-  ]
-)
-
-
-
 dnl This is needed when we want to check for the same function repeatedly
 dnl with other parameters, such as libraries, varying.
 dnl

configure.ac

@@ -417,7 +417,7 @@ AC_SUBST([SCM_I_GSC_HAVE_STRUCT_DIRENT64])
 #   sched.h - missing on MinGW
 #   sys/sendfile.h - non-POSIX, found in glibc
 #
-AC_CHECK_HEADERS([complex.h fenv.h io.h libc.h memory.h process.h \
+AC_CHECK_HEADERS([complex.h fenv.h io.h memory.h process.h \
 sys/dir.h sys/ioctl.h sys/select.h \
 sys/time.h sys/timeb.h sys/times.h sys/stdtypes.h sys/types.h \
 sys/utime.h unistd.h utime.h pwd.h grp.h sys/utsname.h \
@@ -443,8 +443,6 @@ AC_CHECK_TYPE(socklen_t, ,
 
 AC_CHECK_TYPES([struct ip_mreq], , , [#include <netinet/in.h>])
 
-GUILE_HEADER_LIBC_WITH_UNISTD
-
 AC_TYPE_GETGROUPS
 AC_TYPE_SIGNAL
 AC_TYPE_MODE_T

libguile/filesys.c

@@ -58,10 +58,6 @@
 #endif
 #include <time.h>
 
-#ifdef LIBC_H_WITH_UNISTD_H
-#include <libc.h>
-#endif
-
 #ifdef HAVE_PWD_H
 #include <pwd.h>
 #endif

libguile/posix.c

@@ -42,10 +42,6 @@
 #endif
 #include <time.h>
 
-#ifdef LIBC_H_WITH_UNISTD_H
-# include <libc.h>
-#endif
-
 #ifdef HAVE_PWD_H
 # include <pwd.h>
 #endif