Skip src/jni_compiler.cc from llvm backend

LLVM backend has llvm-specific JNI compiler, which
is using different calling convention and being
incompatible with src/jni_compiler.cc, thus we are
not using src/jni_compiler.cc in the llvm backend.

Change-Id: I68a3beb2668b4bcc8ed36aed57fa252907ad2453
diff --git a/build/Android.common.mk b/build/Android.common.mk
index 0dcfd82..1ba92ab 100644
--- a/build/Android.common.mk
+++ b/build/Android.common.mk
@@ -184,7 +184,6 @@
 	src/jdwp/jdwp_handler.cc \
 	src/jdwp/jdwp_main.cc \
 	src/jdwp/jdwp_socket.cc \
-	src/jni_compiler.cc \
 	src/jni_internal.cc \
 	src/logging.cc \
 	src/mark_stack.cc \
@@ -246,6 +245,7 @@
 	src/compiler/SSATransformation.cc \
 	src/compiler/Utility.cc \
 	src/compiler/codegen/RallocUtil.cc \
+	src/jni_compiler.cc \
 	src/jni_internal_arm.cc \
 	src/jni_internal_x86.cc
 ifeq ($(ART_MIPS_TARGET),true)