libosmocodec: add FR bit offset definitions

This change defines the GSM FR bit positions as described
in RFC 3551, which will be used by further ECU
(Error Correction Unit) implementation.

Change-Id: I1d0a198af0f8dd1f690b5a81f5c9eb92c43aefed
diff --git a/include/Makefile.am b/include/Makefile.am
index 4714003..09f5ca6 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -2,6 +2,7 @@
 
 nobase_include_HEADERS = \
                        osmocom/codec/codec.h \
+                       osmocom/codec/gsm610_bits.h \
                        osmocom/core/application.h \
                        osmocom/core/backtrace.h \
                        osmocom/core/bit16gen.h \