Fix compilation with source merging disabled (async-profiler#1185)

Author: fandreuz

src/os_linux.cpp

@@ -8,6 +8,7 @@
 #include <arpa/inet.h>
 #include <byteswap.h>
 #include <dirent.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <sched.h>
 #include <stdio.h>

src/symbols_linux.cpp

@@ -22,6 +22,7 @@
 #include "dwarf.h"
 #include "fdtransferClient.h"
 #include "log.h"
+#include "os.h"
 
 
 #ifdef __x86_64__