Remove references to empty Skia "opts" GNI targets/files

Skia no longer has custom code for ARM+CRC32, nor SSE4.2

Change-Id: I4600b8e74bd91c65ae06ed3241535f74a54e5048
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/107930
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/skia/BUILD.gn b/skia/BUILD.gn
index ff91366..5c0108a 100644
--- a/skia/BUILD.gn
+++ b/skia/BUILD.gn
@@ -415,13 +415,6 @@
 }
 
 # Bits that involve special vector-y hardware.
-if (current_cpu == "arm64") {
-  skia_source_set("skia_opts_crc32") {
-    sources = skia_opts.crc32_sources
-    cflags = [ "-march=armv8-a+crc" ]
-    visibility = [ ":skia_opts" ]
-  }
-}
 if (current_cpu == "x86" || current_cpu == "x64") {
   skia_source_set("skia_opts_sse3") {
     sources = skia_opts.ssse3_sources
@@ -433,16 +426,6 @@
     }
     visibility = [ ":skia_opts" ]
   }
-  skia_source_set("skia_opts_sse42") {
-    sources = skia_opts.sse42_sources
-    if (!is_win || is_clang) {
-      cflags = [ "-msse4.2" ]
-    }
-    if (is_win) {
-      defines = [ "SK_CPU_SSE_LEVEL=42" ]
-    }
-    visibility = [ ":skia_opts" ]
-  }
   skia_source_set("skia_opts_avx") {
     sources = skia_opts.avx_sources
     if (!is_win) {
@@ -491,7 +474,6 @@
       ":skia_opts_hsw",
       ":skia_opts_skx",
       ":skia_opts_sse3",
-      ":skia_opts_sse42",
     ]
   } else if (current_cpu == "arm") {
     # The assembly uses the frame pointer register (r7 in Thumb/r11 in
@@ -509,7 +491,7 @@
       }
     }
   } else if (current_cpu == "arm64") {
-    deps = [ ":skia_opts_crc32" ]
+    # Conditional and empty body needed to avoid assert below
   } else if (current_cpu == "mipsel" || current_cpu == "mips64el") {
     cflags += [ "-fomit-frame-pointer" ]
   } else {