fix integer overflow in elf.h macro SHF_EXCLUDE
diff --git a/include/elf.h b/include/elf.h
index c748c44..1d43670 100644
--- a/include/elf.h
+++ b/include/elf.h
@@ -319,7 +319,7 @@
 #define SHF_MASKOS	     0x0ff00000
 #define SHF_MASKPROC	     0xf0000000
 #define SHF_ORDERED	     (1 << 30)
-#define SHF_EXCLUDE	     (1 << 31)
+#define SHF_EXCLUDE	     (1U << 31)
 
 #define GRP_COMDAT	0x1