utils/conv_gen.py: generate a single file

Instead of generating every convolutional code into a separate
file (such as conv_xcch_gen.c, conv_cs3_gen.c), it is better to
have a single file, containing all definitions, because as many
convolutional codes we add, as many entries we will have to add
into 'src/gsm/Makefile.am'. This approach increases readability
of the Makefile.am, and also makes us able to share some data
between some convolutional code definitions.

For example: xCCH, RACH, SCH, TCH/F, both CS2 and CS3 may use
the same *_state[][2] and *_output[][2] arrays within a single
file. This optimization is currently WIP.

Change-Id: Ib4e4ee5fdde38429e68e3b2fa50ec03a18f59daa
diff --git a/.gitignore b/.gitignore
index 5165364..90c8c85 100644
--- a/.gitignore
+++ b/.gitignore
@@ -110,7 +110,7 @@
 doc/*.tag
 
 src/crc*gen.c
-src/gsm/conv*gen.c
+src/gsm/gsm0503_conv.c
 include/osmocom/core/crc*gen.h
 include/osmocom/core/bit*gen.h