[GN] Define USE_EABI_HARDFLOAT=1 when arm_float_abi=="hard".

Add this define to the config used for mksnapshot. This fixes a bug
where certain applications would fail at runtime on Chromecast.

BUG=592660
LOG=Y
Bug: internal b/27495984

Test: Formerly broken Cast apps load and run as expected.

Review URL: https://codereview.chromium.org/1839763003

Cr-Commit-Position: refs/heads/master@{#35183}

BUILD.gn

@@ -143,7 +143,6 @@ config("toolchain") {
   cflags = []
 
   # TODO(jochen): Add support for arm subarchs, mips, mipsel, mips64el.
-
   if (v8_target_arch == "arm") {
     defines += [ "V8_TARGET_ARCH_ARM" ]
     if (current_cpu == "arm") {
@@ -170,8 +169,13 @@ config("toolchain") {
         "CAN_USE_ARMV7_INSTRUCTIONS",
         "CAN_USE_VFP3_INSTRUCTIONS",
         "CAN_USE_VFP32DREGS",
-        "USE_EABI_HARDFLOAT=0",
       ]
+
+      if (arm_float_abi == "hard") {
+        defines += [ "USE_EABI_HARDFLOAT=1" ]
+      } else if (arm_float_abi == "softfp") {
+        defines += [ "USE_EABI_HARDFLOAT=0" ]
+      }
     }
 
     # TODO(jochen): Add support for arm_test_noprobe.