boot_serial; text size reduction.
 - Remove dependency to sprintf()
 - Remove dependency to cborattr
 - mynewt: replace console with more direct interface to uart
 - mynewt: settings to reduce included os code

Signed-off-by: Marko Kiiskila <marko@runtime.io>
diff --git a/boot/mynewt/syscfg.yml b/boot/mynewt/syscfg.yml
index 778ba5f..3460954 100644
--- a/boot/mynewt/syscfg.yml
+++ b/boot/mynewt/syscfg.yml
@@ -29,5 +29,5 @@
 syscfg.vals:
     SYSINIT_CONSTRAIN_INIT: 0
     OS_SCHEDULING: 0
-    OS_CPUTIME_TIMER_NUM: -1
+    MSYS_1_BLOCK_COUNT: 0
     CONSOLE_COMPAT: 1