benchmarks: Add a microbenchmark for relocation overhead

Allow specification of the many different busyness modes and relocation
interfaces, along with the number of buffers to use and relocations.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/benchmarks/.gitignore b/benchmarks/.gitignore
index 8c39636..1c40a52 100644
--- a/benchmarks/.gitignore
+++ b/benchmarks/.gitignore
@@ -1,6 +1,7 @@
 gem_create
 gem_exec_ctx
 gem_exec_nop
+gem_exec_reloc
 gem_exec_trace
 gem_mmap
 gem_prw