perf tools: Add doc about how to build perf with Asan and UBSan

AddressSanitizer (or ASan) and UndefinedBehaviorSanitizer (or UBSan) are
very useful tools to detect program bugs:

- AddressSanitizer (or ASan) is a GCC feature that detects memory
corruption bugs such as buffer overflows and memory leaks.

- UndefinedBehaviorSanitizer (or UBSan) is a fast undefined behavior
detector supported by GCC. UBSan detects undefined behaviors of programs
at runtime.

This patch adds a document about how to use them on perf. Later patches will fix
some of the issues disclosed by them.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20190316080556.3075-2-changbin.du@gmail.com
[ Make some changes based on comments made by Jiri Olsa ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf build: Add build documentation

Adding file describing the basics of perf build process.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Cc: Alexis Berlemont <alexis.berlemont@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-ibgf7vxyduwohlqqfayl11xb@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>