Remove Emscripten support

lib/Target/JSBackend/MCTargetDesc/LLVMBuild.txt

Index: lib/Target/JSBackend/MCTargetDesc/LLVMBuild.txt
diff --git a/lib/Target/JSBackend/MCTargetDesc/LLVMBuild.txt b/lib/Target/JSBackend/MCTargetDesc/LLVMBuild.txt
deleted file mode 100644
index b7f3e6d89a0021e7555fc06c1fcf5d121d412f5f..0000000000000000000000000000000000000000
--- a/lib/Target/JSBackend/MCTargetDesc/LLVMBuild.txt
+++ /dev/null
@@ -1,24 +0,0 @@
-;===- ./lib/Target/JSBackend/MCTargetDesc/LLVMBuild.txt --------*- Conf -*--===;
-;
-;                     The LLVM Compiler Infrastructure
-;
-; This file is distributed under the University of Illinois Open Source
-; License. See LICENSE.TXT for details.
-;
-;===------------------------------------------------------------------------===;
-;
-; This is an LLVMBuild description file for the components in this subdirectory.
-;
-; For more information on the LLVMBuild system, please see:
-;
-;   http://llvm.org/docs/LLVMBuild.html
-;
-;===------------------------------------------------------------------------===;
-
-[component_0]
-type = Library
-name = JSBackendDesc
-parent = JSBackend
-required_libraries = MC Support JSBackendInfo
-add_to_library_groups = JSBackend
-