[gn build] llvm-lipo, llvm-libtool-darwin symlink targets now dep on binary

This fixes a regression from 69cde915e923d: If llvm_install_cctools_symlinks
is false, depending llvm-lipo:symlinks didn't actually depend on llvm-lipo
and the binary didn't get built as dependency of `check-lld` (because the
`symlinks` array ended up empty).

llvm/utils/gn/secondary/llvm/tools/llvm-libtool-darwin/BUILD.gn

@@ -12,8 +12,9 @@ if (llvm_install_cctools_symlinks) {
 # //:llvm-libtool-darwin depends on this symlink target, see comment in
 # //BUILD.gn.
 group("symlinks") {
+  deps = [ ":llvm-libtool-darwin" ]
   if (llvm_install_cctools_symlinks) {
-    deps = [ ":libtool" ]
+    deps += [ ":libtool" ]
   }
 }
 

llvm/utils/gn/secondary/llvm/tools/llvm-lipo/BUILD.gn

@@ -17,8 +17,9 @@ if (llvm_install_cctools_symlinks) {
 
 # //:llvm-lipo depends on this symlink target, see comment in //BUILD.gn.
 group("symlinks") {
+  deps = [ ":llvm-lipo" ]
   if (llvm_install_cctools_symlinks) {
-    deps = [ ":lipo" ]
+    deps += [ ":lipo" ]
   }
 }