build: Simplify for string.h and getopt.h.

* configure.ac (AC_CHECK_HEADERS): Remove string.h and getopt.h.
* dirmngr/ks-engine-ldap.c: Remove including getopt.h.
* tools/make-dns-cert.c: Likewise.

--

Checking string.h is supported by AC_HEADER_STDC.  Use of getopt.h
is only needed for getopt_long of GNU extention.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

configure.ac

@@ -1358,7 +1358,7 @@ fi
 AC_MSG_NOTICE([checking for header files])
 AC_HEADER_STDC
 AC_HEADER_TIME
-AC_CHECK_HEADERS([string.h unistd.h langinfo.h termio.h locale.h getopt.h \
+AC_CHECK_HEADERS([unistd.h langinfo.h termio.h locale.h \
                   pwd.h inttypes.h signal.h sys/select.h     \
                   stdint.h signal.h termios.h \
                   ucred.h sys/ucred.h sys/sysmacros.h sys/mkdev.h])

dirmngr/ks-engine-ldap.c

@@ -24,9 +24,6 @@
 #include <string.h>
 #include <time.h>
 #include <unistd.h>
-#ifdef HAVE_GETOPT_H
-# include <getopt.h>
-#endif
 #include <stdlib.h>
 #include <npth.h>
 

tools/make-dns-cert.c

@@ -22,9 +22,6 @@
 #endif
 
 #include <unistd.h>
-#ifdef HAVE_GETOPT_H
-#include <getopt.h>
-#endif
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>