[WebAssembly] Update function signature mismatch error message. NFC.

We don't start our error messages with capital letters.

Split out from https://reviews.llvm.org/D48394

Differential Revision: https://reviews.llvm.org/D48400

llvm-svn: 335186
diff --git a/lld/test/wasm/fatal-warnings.ll b/lld/test/wasm/fatal-warnings.ll
index 9bfe95e..0007dc2 100644
--- a/lld/test/wasm/fatal-warnings.ll
+++ b/lld/test/wasm/fatal-warnings.ll
@@ -3,8 +3,8 @@
 ; RUN: lld -flavor wasm -o %t.wasm %t.main.o %t.ret32.o 2>&1 | FileCheck %s -check-prefix=CHECK-WARN
 ; RUN: not lld -flavor wasm --fatal-warnings -o %t.wasm %t.main.o %t.ret32.o 2>&1 | FileCheck %s -check-prefix=CHECK-FATAL
 
-; CHECK-WARN: warning: Function type mismatch: ret32
-; CHECK-FATAL: error: Function type mismatch: ret32
+; CHECK-WARN: warning: function signature mismatch: ret32
+; CHECK-FATAL: error: function signature mismatch: ret32
 
 target triple = "wasm32-unknown-unknown"