lc3: fix pkg-config file lookup

There's a mismatch between the pkg-config file ('lc3')
and the subproject/wrap which meant an installed liblc3
wasn't picked up.

Fixes #2883

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5151>

subprojects/gst-plugins-bad/ext/lc3/meson.build

@@ -4,7 +4,7 @@ lc3_sources = [
   'gstlc3enc.c',
 ]
 
-lc3_dep = dependency('liblc3', required:get_option ('lc3'))
+lc3_dep = dependency('lc3', required:get_option ('lc3'))
 
 if lc3_dep.found()
   gstlc3 = library('gstlc3',

subprojects/liblc3.wrap

@@ -4,3 +4,5 @@ url=https://github.com/google/liblc3.git
 depth=1
 revision=v1.0.3
 
+[provide]
+lc3 = liblc3_dep