Don't attempt to escape % in SparseByteSetBench

Summary: Because it doesn't need to be escaped, and MSVC will warn about invalid escape sequences. If being built with HHVM's settings for MSVC, it's actually an error, as the same warning is produced for multi-byte escape sequences in narrow strings.

Reviewed By: yfeldblum

Differential Revision: D3704596

fbshipit-source-id: 603e57a35f8b7433d1f6e47f4c2882244536b14f

folly/test/SparseByteSetBench.cpp

@@ -127,7 +127,7 @@ void setup_rand_bench() {
         });
     addBenchmark(
         __FILE__,
-        sformat("\%bool_array_set_rand_bench({}, {})",
+        sformat("%bool_array_set_rand_bench({}, {})",
                 size_add, size_contains).c_str(),
         [=](int iters) {
           rand_bench<BoolArraySet>(iters, size_add, size_contains);
@@ -135,7 +135,7 @@ void setup_rand_bench() {
         });
     addBenchmark(
         __FILE__,
-        sformat("\%sparse_byte_set_rand_bench({}, {})",
+        sformat("%sparse_byte_set_rand_bench({}, {})",
                 size_add, size_contains).c_str(),
         [=](int iters) {
           rand_bench<SparseByteSet>(iters, size_add, size_contains);