COFF: Fix typo.

This change doesn't change its functionality since the value
passed here is converted to uint16_t immediately.

llvm-svn: 239271
diff --git a/lld/COFF/Chunks.cpp b/lld/COFF/Chunks.cpp
index f69c235..e485936 100644
--- a/lld/COFF/Chunks.cpp
+++ b/lld/COFF/Chunks.cpp
@@ -88,7 +88,7 @@
   AssocChildren.push_back(Child);
 }
 
-static void add16(uint8_t *P, int32_t V) { write16le(P, read16le(P) + V); }
+static void add16(uint8_t *P, int16_t V) { write16le(P, read16le(P) + V); }
 static void add32(uint8_t *P, int32_t V) { write32le(P, read32le(P) + V); }
 static void add64(uint8_t *P, int64_t V) { write64le(P, read64le(P) + V); }