PPC: fixed the 32bit build

Removed the unnecessary macro.

R=machenbach@chromium.org, dpranke@chromium.org, adamk@chromium.org
BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2949053003
Cr-Commit-Position: refs/heads/master@{#46142}

src/base/build_config.h

@@ -35,7 +35,7 @@
 #define V8_HOST_ARCH_32_BIT 1
 #elif defined(__PPC__) || defined(_ARCH_PPC)
 #define V8_HOST_ARCH_PPC 1
-#if defined(__PPC64__) || defined(_ARCH_PPC64) || defined(_ARCH_PPCGR)
+#if defined(__PPC64__) || defined(_ARCH_PPC64)
 #define V8_HOST_ARCH_64_BIT 1
 #else
 #define V8_HOST_ARCH_32_BIT 1