Build mips64r6 target with GCC.

Use GCC instead of Clang, as the latter generates too large
a stack frame for dex2oat's `main`.

Bug: 27310199
Change-Id: I58d119618292eed2865b15a90239fa6a60779d61
diff --git a/mips64r6/BoardConfig.mk b/mips64r6/BoardConfig.mk
index 47eb1d8..9ba2f8c 100644
--- a/mips64r6/BoardConfig.mk
+++ b/mips64r6/BoardConfig.mk
@@ -27,4 +27,10 @@
 TARGET_SUPPORTS_32_BIT_APPS :=
 TARGET_SUPPORTS_64_BIT_APPS := true
 
-USE_CLANG_PLATFORM_BUILD := true
+# Build with GCC, as building with Clang exhibit the following build
+# error for dex2oat (b/27310199):
+#
+#   art/dex2oat/dex2oat.cc:2606:5: error: stack frame size of 1808
+#   bytes in function 'main' [-Werror,-Wframe-larger-than=]
+#
+USE_CLANG_PLATFORM_BUILD := false