package/pcre2: fix broken URL

As stated on www.pcre.org:

    You can download the current release of the PCRE2 library from its
    official home on GitHub
    [...]
    Note that the former ftp.pcre.org FTP site is no longer available.

Update _SITE URL to the official home on Github.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
[yann.morin.1998@free.fr: use Github, not SourceForge]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/pcre2/pcre2.hash

@@ -1,5 +1,5 @@
-# Locally calculated after checking pgp signature
-# https://ftp.pcre.org/pub/pcre/pcre2-10.37.tar.bz2.sig
+# Locally calculated after checking pgp signature and compared with the mirror on:
+# http://downloads.sourceforge.net/project/pcre/pcre2/10.37/pcre2-10.37.tar.bz2.sig
 sha256  4d95a96e8b80529893b4562be12648d798b957b1ba1aae39606bbc2ab956d270  pcre2-10.37.tar.bz2
 # Locally computed
 sha256  9c9488256e3612ec5ea40fd12abe7ec55a58f23bd36e6f465116c2b3cbffba02  LICENCE

package/pcre2/pcre2.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 PCRE2_VERSION = 10.37
-PCRE2_SITE = https://ftp.pcre.org/pub/pcre
+PCRE2_SITE = https://github.com/PhilipHazel/pcre2/releases/download/pcre2-$(PCRE2_VERSION)
 PCRE2_SOURCE = pcre2-$(PCRE2_VERSION).tar.bz2
 PCRE2_LICENSE = BSD-3-Clause
 PCRE2_LICENSE_FILES = LICENCE