Remove HAVE_STRING_H

The C89 standard and later defines the `<string.h>` header as part of
the standard headers [1] and on current systems it is always present.

Code included also `<strings.h>` header as an alterinative in some
files. This kind of check was relevant on some older systems where the
`<strings.h>` file included definitions for the C89 compliant
`<string.h>`. Today such alternative check is not required anymore. The
`<strings.h>` file is part of the POSIX definition these days.

Also Autoconf suggests doing this and relying on C89 or above [2] and [3].

This patch also cleans few unused `<strings.h>` inclusions in the libmbfl.

[1]: https://port70.net/~nsz/c/c89/c89-draft.html#4.1.2
[2]: http://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/headers.m4
[3]: https://www.gnu.org/software/autoconf/manual/autoconf-2.69/autoconf.html

2 files changed, 1 insertions, 6 deletions

diff --git a/Zend/Zend.m4 b/Zend/Zend.m4
index 8b7971eea1..55a98d6ff3 100644
--- a/Zend/Zend.m4
+++ b/Zend/Zend.m4
@@ -50,7 +50,6 @@ inttypes.h \
 stdint.h \
 limits.h \
 malloc.h \
-string.h \
 unistd.h \
 stdarg.h \
 sys/types.h \
diff --git a/Zend/configure.ac b/Zend/configure.ac
index 5b88ff0ead..8252cfb342 100644
--- a/Zend/configure.ac
+++ b/Zend/configure.ac
@@ -42,11 +42,7 @@ AH_BOTTOM([
 # include <ieeefp.h>
 #endif
 
-#ifdef HAVE_STRING_H
-# include <string.h>
-#else
-# include <strings.h>
-#endif
+#include <string.h>
 
 #if ZEND_BROKEN_SPRINTF
 int zend_sprintf(char *buffer, const char *format, ...);