net/liveMedia: update to 2020.06.25

From the changelog:

2020.06.25:

• Fixed a memory leak in the "sha1()" function (a "EVP_MD_CTX" object was not being deleted). (Thanks to Amir Perlman for reporting this.)

2020.06.23:

• Moved all definitions of PREFIX from "Makefile.tail" files to "Makefile.head" (so that it can be redefined by a "config.*" file, if desired. Also changed the definition of EXE in "config.mingw" to be ".exe". (Thanks to Eric Beuque for this suggestion.)

2020.06.22:

• Fixed a typo in the previous release that could cause a compilation problem for some developers. (Thanks to Eric Beuque for reporting this.)