GN: support 32-bit x86 builds

infra/bots/recipes/swarm_compile.expected/failed_compile.json

Index: infra/bots/recipes/swarm_compile.expected/failed_compile.json
diff --git a/infra/bots/recipes/swarm_compile.expected/failed_compile.json b/infra/bots/recipes/swarm_compile.expected/failed_compile.json
index e36dce5efd9f606857b97f948c5d261dab9f2e9d..b6b22230a5f776accaca2840cb175de9440f695d 100644
--- a/infra/bots/recipes/swarm_compile.expected/failed_compile.json
+++ b/infra/bots/recipes/swarm_compile.expected/failed_compile.json
@@ -35,7 +35,7 @@
       "BUILDTYPE": "Debug",
       "CHROME_HEADLESS": "1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]",
-      "SKIA_OUT": "[CUSTOM_/_B_WORK]/skia/out/Build-Ubuntu-GCC-x86-Debug"
+      "SKIA_OUT": "[CUSTOM_/_B_WORK]/skia/out/Build-Ubuntu-GCC-x86_64-Debug"
     },
     "name": "gclient setup"
   },
@@ -64,7 +64,7 @@
       "BUILDTYPE": "Debug",
       "CHROME_HEADLESS": "1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]",
-      "SKIA_OUT": "[CUSTOM_/_B_WORK]/skia/out/Build-Ubuntu-GCC-x86-Debug"
+      "SKIA_OUT": "[CUSTOM_/_B_WORK]/skia/out/Build-Ubuntu-GCC-x86_64-Debug"
     },
     "name": "gclient sync",
     "~followup_annotations": [
@@ -95,7 +95,7 @@
       "BUILDTYPE": "Debug",
       "CHROME_HEADLESS": "1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]",
-      "SKIA_OUT": "[CUSTOM_/_B_WORK]/skia/out/Build-Ubuntu-GCC-x86-Debug"
+      "SKIA_OUT": "[CUSTOM_/_B_WORK]/skia/out/Build-Ubuntu-GCC-x86_64-Debug"
     },
     "name": "gclient recurse (git config user.name)"
   },
@@ -115,7 +115,7 @@
       "BUILDTYPE": "Debug",
       "CHROME_HEADLESS": "1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]",
-      "SKIA_OUT": "[CUSTOM_/_B_WORK]/skia/out/Build-Ubuntu-GCC-x86-Debug"
+      "SKIA_OUT": "[CUSTOM_/_B_WORK]/skia/out/Build-Ubuntu-GCC-x86_64-Debug"
     },
     "name": "gclient recurse (git config user.email)"
   },
@@ -129,9 +129,9 @@
       "BUILDTYPE": "Debug",
       "CHROME_HEADLESS": "1",
       "CHROME_PATH": "[SLAVE_BUILD]/src",
-      "GYP_DEFINES": "skia_arch_type=x86 skia_warnings_as_errors=1",
+      "GYP_DEFINES": "skia_arch_type=x86_64 skia_warnings_as_errors=1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]",
-      "SKIA_OUT": "[CUSTOM_/_B_WORK]/skia/out/Build-Ubuntu-GCC-x86-Debug"
+      "SKIA_OUT": "[CUSTOM_/_B_WORK]/skia/out/Build-Ubuntu-GCC-x86_64-Debug"
     },
     "name": "build most",
     "~followup_annotations": [