Fix common typo in comments, warning and error messages.

s/can not/cannot/g

Change-Id: I1bac31157732666deb46f6f20389ff539977ffb9
diff --git a/core/definitions.mk b/core/definitions.mk
index 12dce3d..5600779 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -1768,7 +1768,7 @@
 # Copy a single file from one place to another,
 # preserving permissions and overwriting any existing
 # file.
-# We disable the "-t" option for acp can not handle
+# We disable the "-t" option for acp cannot handle
 # high resolution timestamp correctly on file systems like ext4.
 # Therefore copy-file-to-target is the same as copy-file-to-new-target.
 define copy-file-to-target