Disable PEAR by default

Installation of PEAR can be enabled using --with-pear, but will
through a deprecation warning during ./configure.

UPGRADING

@@ -47,6 +47,11 @@ PHP 7.4 UPGRADE NOTES
     function does not throw, so explicitly checking it is not necessary.
     RFC: http://php.net/manual/de/function.openssl-random-pseudo-bytes.php
 
+- PEAR:
+  . Installation of PEAR (including PECL) is no longer enabled by default. It
+    can be explicitly enabled using --with-pear. This option is deprecated and
+    may be removed in the future.
+
 - PDO:
   . Attempting to serialize a PDO or PDOStatement instance will now generate
     an Exception rather than a PDOException, consistent with other internal
@@ -145,8 +150,8 @@ PHP 7.4 UPGRADE NOTES
     pattern will be interpreted as a string instead.
 
 - LDAP:
-  . ldap_control_paged_result_response and ldap_control_paged_result are deprecated.
-    Pagination controls can be sent along with ldap_search instead.
+  . ldap_control_paged_result_response and ldap_control_paged_result are
+    deprecated. Pagination controls can be sent along with ldap_search instead.
 
 ========================================
 5. Changed Functions

configure.ac

@@ -1136,8 +1136,7 @@ if test "$PHP_CLI" = "no"; then
 fi
 
 PHP_ARG_WITH(pear, [whether to install PEAR],
-[  --with-pear=DIR         Install PEAR in DIR @<:@PREFIX/lib/php@:>@
-  --without-pear          Do not install PEAR], DEFAULT, yes)
+[  --with-pear=DIR         Install PEAR in DIR @<:@PREFIX/lib/php@:>@], no, yes)
 
 if test "$PHP_PEAR" != "no"; then
 
@@ -1153,10 +1152,12 @@ if test "$PHP_PEAR" != "no"; then
     AC_MSG_ERROR([$pear_error_msg])
   fi
 
+  AC_MSG_WARN([The --with-pear option is deprecated])
+
   install_pear="install-pear"
   PEAR_INSTALLDIR=$PHP_PEAR
 
-  if test "$PHP_PEAR" = "DEFAULT" || test "$PHP_PEAR" = "yes"; then
+  if test "$PHP_PEAR" = "yes"; then
     case $PHP_LAYOUT in
       GNU) PEAR_INSTALLDIR=$datadir/pear;;
       *)   PEAR_INSTALLDIR=$libdir/php;;