Fix arch checks

Some devices have a 32-bit userspace but a 64-bit kernel. These
devices need to have 32-bit gapps, not 64-bit ones. To fix this,
switch to getting arch from ro.bionic.arch instead of uname -m.
Additionally, remove the nice_arch function as it makes debugging
issues more difficult when the nice arch matches but the underlying
values don't line up.

build/main.mk

@@ -11,11 +11,11 @@ distclean:
 
 gapps_arm:
 	@echo "Compiling GApps for arm..."
-	@bash $(BUILD_GAPPS) arm armv7l 2>&1
+	@bash $(BUILD_GAPPS) arm 2>&1
 
 gapps_arm64:
 	@echo "Compiling GApps for arm64..."
-	@bash $(BUILD_GAPPS) arm64 aarch64 2>&1
+	@bash $(BUILD_GAPPS) arm64 2>&1
 
 gapps_x86:
 	@echo "Compiling GApps for x86..."