Fixed PCRE url

As stated in https://pcre.org/, PCRE has been moved to sourceforge
and the old FTP is no longer available.

library_builders.sh

@@ -424,10 +424,9 @@ function build_netcdf {
         && make -j4 \
         && make install)
     touch netcdf-stamp
-}
 
 function build_pcre {
-    build_simple pcre $PCRE_VERSION https://ftp.pcre.org/pub/pcre
+    build_simple pcre $PCRE_VERSION https://sourceforge.net/projects/pcre/files/pcre/${PCRE_VERSION}
 }
 
 function build_swig {