build_kernel.sh: Use 4.9 gcc by default for mips

There is no mips 4.8 toolchain in the prebuilts anymore.
4.9 GCC should be used for building goldfish kernel.

Change-Id: I84f17909aefb2d4d2749d8a543980583d8601896
diff --git a/build-kernel.sh b/build-kernel.sh
index beb5984..f0d25b6 100755
--- a/build-kernel.sh
+++ b/build-kernel.sh
@@ -171,6 +171,9 @@
     if [ "$ARCH" = "mips64" ]; then
         GCC_VERSION=4.9
     fi
+    if [ "$ARCH" = "mips" ]; then
+        GCC_VERSION=4.9
+    fi
     echo "Autoconfig: --gcc-version=$GCC_VERSION"
 fi
 
@@ -251,7 +254,7 @@
             CROSSPREFIX=x86_64-linux-android-
             ;;
         mips)
-            CROSSPREFIX=mipsel-linux-android-
+            CROSSPREFIX=mips64el-linux-android-
             ;;
         mips64)
             CROSSPREFIX=mips64el-linux-android-