[gn build] Unbreak link after 9ebaf4f

9ebaf4f removed one of two redundant deps in CMake, but it removed the
one dep in the GN build. Since the CMake build still has the dep, so should the
GN build. (Things don't link without it.)

Author: nico

llvm/utils/gn/secondary/llvm/lib/Transforms/IPO/BUILD.gn

@@ -14,6 +14,7 @@ static_library("IPO") {
     "//llvm/lib/Transforms/AggressiveInstCombine",
     "//llvm/lib/Transforms/InstCombine",
     "//llvm/lib/Transforms/Instrumentation",
+    "//llvm/lib/Transforms/Scalar",
     "//llvm/lib/Transforms/Utils",
     "//llvm/lib/Transforms/Vectorize",
   ]