Fix android build of the new process launcher

Android does not define the "cross-platform" symbol PT_TRACE_ME. Define
it ourselves, so we can keep the rest of the code generic.

llvm-svn: 293779

lldb/source/Host/posix/ProcessLauncherPosixFork.cpp

@@ -23,6 +23,7 @@
 
 #ifdef __ANDROID__
 #include <android/api-level.h>
+#define PT_TRACE_ME PTRACE_TRACEME
 #endif
 
 #if defined(__ANDROID_API__) && __ANDROID_API__ < 21