OS::ArmUsingHardFloat returns bogus value for clang-built chrome.

This caused a runtime crash for Chrome built with clang on all
ChromeOs
arm32 platforms - ChromeOs chrome is using hardfp while this routine
returns false.

The fix is straightforward.

BUG=chromium:586219
TEST=built arm32 hardfp using clang and passed all tests.
LOG=N

Review URL: https://codereview.chromium.org/1733863002

Cr-Commit-Position: refs/heads/master@{#34367}

src/base/platform/platform-linux.cc

@@ -72,14 +72,14 @@ bool OS::ArmUsingHardFloat() {
 #define GCC_VERSION (__GNUC__ * 10000                                          \
                      + __GNUC_MINOR__ * 100                                    \
                      + __GNUC_PATCHLEVEL__)
-#if GCC_VERSION >= 40600
+#if GCC_VERSION >= 40600 && !defined(__clang__)
 #if defined(__ARM_PCS_VFP)
   return true;
 #else
   return false;
 #endif
 
-#elif GCC_VERSION < 40500
+#elif GCC_VERSION < 40500 && !defined(__clang__)
   return false;
 
 #else
@@ -89,7 +89,7 @@ bool OS::ArmUsingHardFloat() {
       !defined(__VFP_FP__)
   return false;
 #else
-#error "Your version of GCC does not report the FP ABI compiled for."          \
+#error "Your version of compiler does not report the FP ABI compiled for."     \
        "Please report it on this issue"                                        \
        "http://code.google.com/p/v8/issues/detail?id=2140"