lib: use flb_compat.h instead of unistd.h (Windows issue)

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>

Author: edsiper

src/flb_lib.c

@@ -20,6 +20,7 @@
 
 #include <fluent-bit/flb_lib.h>
 #include <fluent-bit/flb_mem.h>
+#include <fluent-bit/flb_compat.h>
 #include <fluent-bit/flb_pipe.h>
 #include <fluent-bit/flb_engine.h>
 #include <fluent-bit/flb_input.h>
@@ -39,7 +40,6 @@
 #include <signal.h>
 #include <stdarg.h>
 #include <sys/stat.h>
-#include <unistd.h>
 #include <errno.h>
 #include <stdlib.h>