Compilation fix for newer mbed-os

Fork of X_NUCLEO_IDB0XA1 by ST

Revision:
129:d5686dd11391
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/.gitignore	Tue Oct 06 13:59:23 2015 +0200
@@ -0,0 +1,9 @@
+# vim temporary files
+*.sw*
+
+# yotta files
+build
+yotta_modules
+yotta_targets
+.yotta.json
+upload.tar.gz