MIPS: Resolve chromium and android webview build conflicts.

The mips related gyp variables and compiler flags for webview
and chromium builds are set externally. The CL ensures this
behaviour and prevents conflicts in configuration with standalone builds.

TEST=
BUG=
R=jkummerow@chromium.org, paul.lind@imgtec.com

Review URL: https://codereview.chromium.org/707883002

Cr-Commit-Position: refs/heads/master@{#25243}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25243 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

build/standalone.gypi

@@ -127,6 +127,16 @@
     'arm_fpu%': 'vfpv3',
     'arm_float_abi%': 'default',
     'arm_thumb': 'default',
+
+    # Default MIPS variable settings.
+    'mips_arch_variant%': 'r2',
+    # Possible values fp32, fp64, fpxx.
+    # fp32 - 32 32-bit FPU registers are available, doubles are placed in
+    #        register pairs.
+    # fp64 - 32 64-bit FPU registers are available.
+    # fpxx - compatibility mode, it chooses fp32 or fp64 depending on runtime
+    #        detection
+    'mips_fpu_mode%': 'fp32',
   },
   'target_defaults': {
     'variables': {