openssl: Fix build on iOS
openssl: Only create .la files on non-iOS
libsrtp.recipe: Use 1.5.0 release instead of git master

When I made the recipe at first, there was no release. It's better to use one.
openh264.recipe: Add some comments for the next person to update the recipe
libsrtp, openh264, openssl: Also add the dependency libs
openssl: Fix typo while adding LDFLAGS
libsrtp/openh264/openssl: Hopefully fix dependency_libs for real
recipes: gst-plugins-bad: Allow using system libraries

We now have plugins that use system libraries on linux (such as GL or
X11)
config: android: Don't allow using system libraries

Might be unfortunate to pick up linux headers/libraries when we're
targetting android :)
gitignore: Ignore rpm files
gettext: Also build depend on iconv on iOS