Modify argument parser for multiple arguments.

Currently, if a test is created like this:

  BIONIC_BENCHMARK_WITH_ARG(BM_bench, "16");

Everything works as expected, a benchmark is created of BM_bench/16.
However, it is not possible to specify a benchmark should be called with
one argument, but iterate over different values. The example:

  BIONIC_BENCHMARK_WITH_ARG(BM_bench, "16 32");

Creates a single benchmark run with two arguments:

  BM_bench/16/32

This change modifies the algorithm to make it possible to create multiple
instances of the benchmark iterating over each argument as a single
argument. After this change, two benchmarks are executed:

  BM_bench/16
  BM_bench/32

To do the previous behavior, use:

  BIONIC_BENCHMARK_WITH_ARG(BM_bench, "16/32");

This will create a single benchmark with two args. This format does
not support spaces in the args, so "16 / 32" is not valid.

Modified the test_small.xml to use the new format.

Test: All unit tests pass.
Change-Id: I6f486e1d4a90580c3dace0581ea65f439911ef5a
diff --git a/benchmarks/tests/interface_test.cpp b/benchmarks/tests/interface_test.cpp
index e7b96d5..1d620d1 100644
--- a/benchmarks/tests/interface_test.cpp
+++ b/benchmarks/tests/interface_test.cpp
@@ -192,9 +192,11 @@
 
 TEST_F(SystemTests, small) {
   std::string expected =
-    "BM_string_memcmp/8/8/8/iterations:1\n"
-    "BM_math_sqrt/iterations:1\n"
-    "BM_property_get/1/iterations:1\n";
+      "BM_string_memcmp/8/8/8/iterations:1\n"
+      "BM_math_sqrt/iterations:1\n"
+      "BM_property_get/1/iterations:1\n"
+      "BM_property_get/2/iterations:1\n"
+      "BM_property_get/3/iterations:1\n";
   Verify(expected, 0, std::vector<const char*>{GetBionicXmlArg("test_small.xml").c_str(),
                                                "--bionic_iterations=1"});
 }
@@ -238,17 +240,18 @@
   std::string expected =
     "BM_string_memcpy/8/8/8/iterations:1\n"
     "BM_math_log10/iterations:1\n";
-  Verify(expected, 0, std::vector<const char*>{"--bionic_extra=BM_string_memcpy 8 8 8",
-                                               "--bionic_extra=BM_math_log10",
-                                               "--bionic_iterations=1"});
+  Verify(expected, 0,
+         std::vector<const char*>{"--bionic_extra=BM_string_memcpy 8/8/8",
+                                  "--bionic_extra=BM_math_log10", "--bionic_iterations=1"});
 }
 
 TEST_F(SystemTests, cmd_args_no_iter) {
   std::string expected =
     "BM_string_memcpy/8/8/8\n"
     "BM_math_log10\n";
-  Verify(expected, 0, std::vector<const char*>{"--bionic_extra=BM_string_memcpy 8 8 8",
-                                               "--bionic_extra=BM_math_log10"});
+  Verify(expected, 0,
+         std::vector<const char*>{"--bionic_extra=BM_string_memcpy 8/8/8",
+                                  "--bionic_extra=BM_math_log10"});
 }
 
 TEST_F(SystemTests, xml_and_args) {