Disable sktexttopdf when building for mipsel.

The Clang in the latest NDK crashes when we try to build it for MIPS.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2286303004

Review-Url: https://codereview.chromium.org/2286303004
diff --git a/BUILD.gn b/BUILD.gn
index 8454e4b..67347ea 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -804,15 +804,17 @@
     testonly = true
   }
 
-  executable("sktexttopdf") {
-    sources = [
-      "tools/SkShaper_harfbuzz.cpp",
-      "tools/using_skia_and_harfbuzz.cpp",
-    ]
-    deps = [
-      ":skia",
-      "//third_party/harfbuzz",
-    ]
-    testonly = true
+  if (current_cpu != "mipsel") {  # Clang 3.8 crashes while compiling hb-icu.cc for mipsel.
+    executable("sktexttopdf") {
+      sources = [
+        "tools/SkShaper_harfbuzz.cpp",
+        "tools/using_skia_and_harfbuzz.cpp",
+      ]
+      deps = [
+        ":skia",
+        "//third_party/harfbuzz",
+      ]
+      testonly = true
+    }
   }
 }