Added Android x86_64 support to the build compiled using standalone NDK.
It needs a separate ANDROID_NDK define instead of re-using ANDROID and/or ANDROID defines because different version of NDK for different targets (arm vs x86 for example) seem to have some include path differences.
This change does require some changes in LLVM. The patch for that was submitted separately.
This doesn't look correct. Now every file that includes LLDBDependencies will have a custom command that builds tools/lldb/source/LLDB_vers.c. With ninja, this causes "ninja: warning: multiple rules generate tools/lldb/source/LLDB_vers.c. builds involving this target will not be correct; continuing anyway" for example (since there's more than one CMakeLists.txt that includes LLDBDependencies.txt).
Maybe this rule could stay where it was?