Avoid confusing "read prevented write" log messages.

Moving to a "function: message" style avoids ambiguity.

Change-Id: If9d590e50265c61725d3673bd03796e65edd2d5e
diff --git a/libc/bionic/__read_chk.cpp b/libc/bionic/__read_chk.cpp
index 9de99c1..ff50983 100644
--- a/libc/bionic/__read_chk.cpp
+++ b/libc/bionic/__read_chk.cpp
@@ -32,11 +32,11 @@
 
 extern "C" ssize_t __read_chk(int fd, void* buf, size_t count, size_t buf_size) {
   if (__predict_false(count > buf_size)) {
-    __fortify_chk_fail("read prevented write past end of buffer", 0);
+    __fortify_chk_fail("read: prevented write past end of buffer", 0);
   }
 
   if (__predict_false(count > SSIZE_MAX)) {
-    __fortify_chk_fail("read count > SSIZE_MAX", 0);
+    __fortify_chk_fail("read: count > SSIZE_MAX", 0);
   }
 
   return read(fd, buf, count);