logd: regression in log_strtok_r

In commit 'logd: fix kernel logline stutter'
2c3b300fd8307e8da13608197d0a89bc613de5fb we introduced log_strtok_r.
as a replacement for strtok_r that dealt with a problem with
some kernel log messages. Fix is to refine definition of
is_timestamp to not match on patterns like [0].

Change-Id: I0867a555a3bca09bbf18d18e75e41dffffe57a22
diff --git a/logd/LogKlog.cpp b/logd/LogKlog.cpp
index 7d14648..4e0e896 100644
--- a/logd/LogKlog.cpp
+++ b/logd/LogKlog.cpp
@@ -68,6 +68,9 @@
             continue;
         }
         if (!isdigit(c) && (c == ']')) {
+            if (first_period || (*s != ' ')) {
+                break;
+            }
             return s;
         }
     }
@@ -75,7 +78,7 @@
 }
 
 // Like strtok_r with "\r\n" except that we look for log signatures (regex)
-//   \(\(<[0-9]+>\)\([[] *[0-9]+[]]\)\{0,1\}\|[[] *[0-9]+[]]\)
+// \(\(<[0-9]+>\)\([[] *[0-9]+[.][0-9]+[]] \)\{0,1\}\|[[] *[0-9]+[.][0-9]+[]] \)
 // and split if we see a second one without a newline.
 
 #define SIGNATURE_MASK     0xF0