gnu: pjproject-jami: Fix CVE-2020-15260 and CVE-2021-21375.

gnu: pjproject-jami: Fix CVE-2020-15260 and CVE-2021-21375.

The custom pjproject package used by Jami is updated with the latest patches
found in the 20210326.1.cfba013 release of Jami.

* gnu/packages/jami.scm (%jami-version): Update to 20210326.1.cfba013.
(jami-source) [snippet]: Update comment.  Add client-electron and client-ios
to the list of deleted directories.  Remove client-windows from the list, as
it no longer exists.
(jami-apply-dependency-patches): Update comment.  Ignore whitespace
when applying patches, otherwise the pjproject patches would not apply.
(pjproject-jami): Add comment.
[source]: Define the source; the parent pjproject package was
updated was updated to 2.11, but the patches only apply against 2.10.
[phases] <apply-patches>: Update the list of patches used with those found in
the release tarball.