require system pcre2 in rpms

now when SLES12.3 is gone, we can enforce it

cmake/build_configurations/mysql_release.cmake

@@ -106,8 +106,7 @@ ELSEIF(RPM)
   SET(SEMODULE_PACKAGE /usr/bin/semodule_package CACHE FILEPATH "")
   SET(PLUGIN_AUTH_SOCKET YES CACHE STRING "")
   SET(WITH_EMBEDDED_SERVER ON CACHE BOOL "")
-  # not yet, SLES 12.3 doesn't provide pcre2
-  #SET(WITH_PCRE system CACHE STRING "")
+  SET(WITH_PCRE system CACHE STRING "")
   IF(RPM MATCHES "fedora|centos|rhel")
     SET(WITH_INNODB_BZIP2 OFF CACHE STRING "")
     SET(WITH_INNODB_LZO OFF CACHE STRING "")
@@ -137,7 +136,6 @@ ELSE()
   SET(WITH_JEMALLOC static CACHE STRING "")
   SET(PLUGIN_AUTH_SOCKET STATIC CACHE STRING "")
   SET(WITH_STRIPPED_CLIENT ON CACHE BOOL "Strip all client binaries")
-  SET(WITH_PCRE bundled CACHE STRING "")
   SET(WITH_INNODB_BZIP2 OFF CACHE STRING "")
   SET(WITH_INNODB_LZ4 OFF CACHE STRING "")
   SET(WITH_INNODB_LZO OFF CACHE STRING "")