Revert of GN: support 32-bit x86 builds

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 46d443474f2fde881c22cdc9751f4e3f02a8e7ab..05fe3500ffdaa5335346ef07fc57f55144008bfe 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -554,26 +554,22 @@
   ]
 }
 
-if (target_cpu == "x64") {
-  # Our bots only have 64-bit libOSMesa installed.
-  # TODO: worth fixing?
-  executable("fiddle") {
-    include_dirs = [ "$target_gen_dir" ]
-    libs = []
-    if (is_linux) {
-      libs += [ "OSMesa" ]
-    }
-
-    sources = [
-      "src/images/SkForceLinking.cpp",
-      "tools/fiddle/draw.cpp",
-      "tools/fiddle/fiddle_main.cpp",
-    ]
-    deps = [
-      ":skia",
-      ":skia.h",
-    ]
-  }
+executable("fiddle") {
+  include_dirs = [ "$target_gen_dir" ]
+  libs = []
+  if (is_linux) {
+    libs += [ "OSMesa" ]
+  }
+
+  sources = [
+    "src/images/SkForceLinking.cpp",
+    "tools/fiddle/draw.cpp",
+    "tools/fiddle/fiddle_main.cpp",
+  ]
+  deps = [
+    ":skia",
+    ":skia.h",
+  ]
 }
 
 # Targets guarded by skia_enable_tools may use //third_party freely.