common: Add pre and de emphasis, if the radio does not support it

Connect to the oscillator of the transmitter - good girl!
You need to enable pre emphasis in this case.

Connect to the discriminator of the receiver - good boy!
You need to enable de emphasis in this case.

src/test/Makefile.am

@@ -1,7 +1,8 @@
 AM_CPPFLAGS = -Wall -g $(all_includes)
 
 noinst_PROGRAMS = \
-	test_compander
+	test_compander \
+	test_emphasis
 
 test_compander_SOURCES = test_compander.c
 
@@ -10,3 +11,10 @@ test_compander_LDADD = \
 	$(top_builddir)/src/common/libcommon.a \
 	-lm
 
+test_emphasis_SOURCES = test_emphasis.c
+
+test_emphasis_LDADD = \
+	$(COMMON_LA) \
+	$(top_builddir)/src/common/libcommon.a \
+	-lm
+