build: Don't use the deprecated INCLUDES in the various Makefile.am

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/src/codec/Makefile.am b/src/codec/Makefile.am
index 665768c..6110cbf 100644
--- a/src/codec/Makefile.am
+++ b/src/codec/Makefile.am
@@ -2,8 +2,7 @@
 # Please read Chapter 6 "Library interface versions" of the libtool documentation before making any modification
 LIBVERSION=0:0:0
 
-INCLUDES = $(all_includes) -I$(top_srcdir)/include
-AM_CFLAGS = -Wall
+AM_CFLAGS = -Wall $(all_includes) -I$(top_srcdir)/include
 
 lib_LTLIBRARIES = libosmocodec.la