Add new strcmp/strncmp benchmark

This patch adds a new strcmp/strcmp benchmark with different set of
inputs.  It cover all pre-defined range values (small, medium, large)
for aligned inputs and also small range for unaligned ones.

Test: Ran new string test suite with a single bionic iteration.
Change-Id: Ice78d74c3583a33158eaba3309c10df54044aa28
diff --git a/benchmarks/test_suites/test_strcmp.xml b/benchmarks/test_suites/test_strcmp.xml
new file mode 100644
index 0000000..17d1b83
--- /dev/null
+++ b/benchmarks/test_suites/test_strcmp.xml
@@ -0,0 +1,20 @@
+<fn>
+  <name>BM_string_strcmp</name>
+  <args>AT_TWOBUF_MANUAL_ALIGN1_0_ALIGN2_0_SIZE_SMALL</args>
+</fn>
+<fn>
+  <name>BM_string_strcmp</name>
+  <args>AT_TWOBUF_MANUAL_ALIGN1_0_ALIGN2_0_SIZE_MEDIUM</args>
+</fn>
+<fn>
+  <name>BM_string_strcmp</name>
+  <args>AT_TWOBUF_MANUAL_ALIGN1_4_ALIGN2_0_SIZE_SMALL</args>
+</fn>
+<fn>
+  <name>BM_string_strcmp</name>
+  <args>AT_TWOBUF_MANUAL_ALIGN1_0_ALIGN2_4_SIZE_SMALL</args>
+</fn>
+<fn>
+  <name>BM_string_strcmp</name>
+  <args>AT_TWOBUF_MANUAL_ALIGN1_4_ALIGN2_4_SIZE_SMALL</args>
+</fn>
diff --git a/benchmarks/test_suites/test_strncmp.xml b/benchmarks/test_suites/test_strncmp.xml
new file mode 100644
index 0000000..42299fc
--- /dev/null
+++ b/benchmarks/test_suites/test_strncmp.xml
@@ -0,0 +1,20 @@
+<fn>
+  <name>BM_string_strncmp</name>
+  <args>AT_TWOBUF_MANUAL_ALIGN1_0_ALIGN2_0_SIZE_SMALL</args>
+</fn>
+<fn>
+  <name>BM_string_strncmp</name>
+  <args>AT_TWOBUF_MANUAL_ALIGN1_0_ALIGN2_0_SIZE_MEDIUM</args>
+</fn>
+<fn>
+  <name>BM_string_strncmp</name>
+  <args>AT_TWOBUF_MANUAL_ALIGN1_4_ALIGN2_0_SIZE_SMALL</args>
+</fn>
+<fn>
+  <name>BM_string_strncmp</name>
+  <args>AT_TWOBUF_MANUAL_ALIGN1_0_ALIGN2_4_SIZE_SMALL</args>
+</fn>
+<fn>
+  <name>BM_string_strncmp</name>
+  <args>AT_TWOBUF_MANUAL_ALIGN1_4_ALIGN2_4_SIZE_SMALL</args>
+</fn>