Mark libraries required by libbcinfo as vendor_available

libLLVMBitWriter_3_2 and libStripUnkAttr are used by libbcinfo, which is
a vndk-sp library. Mark them as vendor_available:true so that they are
available when building libbcinfo.so

Bug: 64425518
Test: BOARD_VNDK_VERSION=current m -j libbcinfo.so
Change-Id: I7a59aabcae0207d9d4a19df11c89d0008ddbb039
2 files changed