Allow ia32 and arm builds to fail for now

The ia32 and arm libchromiumcontent can not build on CI for now.

.travis.yml

@@ -17,5 +17,8 @@ matrix:
       env: TARGET_ARCH=arm
     - os: linux
       env: TARGET_ARCH=ia32
+  allow_failures:
+    - env: TARGET_ARCH=arm
+    - env: TARGET_ARCH=ia32
 
 script: './script/cibuild'