Add Mips to the list of clang targets in setup.sh

Summary:
Mips is included in the list of targets we build against with ndk-build,
so we need to bring it back. Still, building clang for 4 targets is more
efficient than building it for 16.

{F174304520}

Test Plan: Run ./setup.sh, observe mips getting picked up as a target during configure.

Reviewers: mtrojer, jul

Reviewed By: mtrojer

Differential Revision: https://phabricator.intern.facebook.com/D16646418

Signature: 16646418:1565007816:a9169af4550a29cde9dc3adaa79b05ef6dbf16e1

clang/setup.sh

@@ -124,7 +124,7 @@ CMAKE_ARGS=(
   -DLLVM_ENABLE_EH=On
   -DLLVM_ENABLE_RTTI=On
   -DLLVM_INCLUDE_DOCS=Off
-  -DLLVM_TARGETS_TO_BUILD="X86;AArch64;ARM"
+  -DLLVM_TARGETS_TO_BUILD="X86;AArch64;ARM;Mips"
   -DLLVM_BUILD_EXTERNAL_COMPILER_RT=On
 )