Separate the lines received in a single read.

Fixes the case where multiple lines are read in a single read syscall
(it could be better optimized in the future). Also fixes a memory
corruption issue when rec == 0.

i3bar/include/common.h

@@ -14,6 +14,7 @@ typedef int bool;
 
 struct ev_loop* main_loop;
 char            *statusline;
+char            *statusline_buffer;
 
 struct rect_t {
 	int	x;