Remove mergesort implementation

php_mergesort() isn't being used for anything, and hasn't been for
a long time. Even if we wanted to use a stable sort, this isn't
the implementation we'd use...

Author: nikic

configure.ac

@@ -1439,7 +1439,7 @@ PHP_ADD_SOURCES(TSRM, TSRM.c, -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1)
 PHP_ADD_SOURCES(main, main.c snprintf.c spprintf.c \
        fopen_wrappers.c alloca.c  php_scandir.c \
        php_ini.c SAPI.c rfc1867.c php_content_types.c strlcpy.c \
-       strlcat.c explicit_bzero.c mergesort.c reentrancy.c php_variables.c php_ticks.c \
+       strlcat.c explicit_bzero.c reentrancy.c php_variables.c php_ticks.c \
        network.c php_open_temporary_file.c \
        output.c getopt.c php_syslog.c, -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1)
 

main/mergesort.c

@@ -360,7 +360,6 @@ END_EXTERN_C()
 BEGIN_EXTERN_C()
 PHPAPI extern int (*php_register_internal_extensions_func)(void);
 PHPAPI int php_register_internal_extensions(void);
-PHPAPI int php_mergesort(void *base, size_t nmemb, size_t size, int (*cmp)(const void *, const void *));
 PHPAPI void php_register_pre_request_shutdown(void (*func)(void *), void *userdata);
 PHPAPI void php_com_initialize(void);
 PHPAPI char *php_get_current_user(void);

main/php.h

@@ -248,7 +248,7 @@ if (VS_TOOLSET && VCVERS >= 1914) {
 
 ADD_SOURCES("main", "main.c snprintf.c spprintf.c getopt.c fopen_wrappers.c \
 	php_scandir.c php_ini.c SAPI.c rfc1867.c php_content_types.c strlcpy.c \
-	strlcat.c mergesort.c reentrancy.c php_variables.c php_ticks.c network.c \
+	strlcat.c reentrancy.c php_variables.c php_ticks.c network.c \
 	php_open_temporary_file.c output.c internal_functions.c \
 	php_syslog.c");
 ADD_FLAG("CFLAGS_BD_MAIN", "/D ZEND_ENABLE_STATIC_TSRMLS_CACHE=1");