rename bscconfig.h to config.h, cleanup

Get rid of the legacy name bscconfig.h from osmo-nitb times.

Remove the #include from some of the files that aren't actually using it.

Instead of '#include "../../config.h"', use plain '#include "config.h"'
because we're anyway passing $top_srcdir as -I during compilation.

Change-Id: Id4f683be1f36f0630c83da54e02868aae847aeec
diff --git a/configure.ac b/configure.ac
index ae6dd6a..36ff99e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -237,7 +237,7 @@
 AC_MSG_RESULT([CPPFLAGS="$CPPFLAGS"])
 
 dnl Generate the output
-AM_CONFIG_HEADER(bscconfig.h)
+AM_CONFIG_HEADER(config.h)
 
 AC_OUTPUT(
     include/Makefile