[gn build] Fix llvm-gsymutil after D75291

Author: MaskRay

llvm/utils/gn/secondary/llvm/test/BUILD.gn

@@ -216,7 +216,7 @@ group("test") {
     "//llvm/tools/llvm-elfabi",
     "//llvm/tools/llvm-exegesis",
     "//llvm/tools/llvm-extract",
-    "//llvm/tools/llvm-gsymutil:llvm-gsymutil"
+    "//llvm/tools/llvm-gsymutil:llvm-gsymutil",
     "//llvm/tools/llvm-ifs",
     "//llvm/tools/llvm-isel-fuzzer",
     "//llvm/tools/llvm-jitlink",