bench: Add test for function call overhead.

For a trivial operation, calling a function is 5 times slower than doing
operation inline.

tests/bench/funcall-1-inline.py

@@ -0,0 +1,9 @@
+# Function call overhead test
+# Establish a baseline for performing a trivial operation inline
+import bench
+
+def test(num):
+    for i in iter(range(num)):
+        a = i + 1
+
+bench.run(test)

tests/bench/funcall-2-funcall.py

@@ -0,0 +1,12 @@
+# Function call overhead test
+# Perform the same trivial operation as global function call
+import bench
+
+def f(x):
+    return x + 1
+
+def test(num):
+    for i in iter(range(num)):
+        a = f(i)
+
+bench.run(test)

tests/bench/funcall-3-funcall-local.py

@@ -0,0 +1,16 @@
+# Function call overhead test
+# Perform the same trivial operation as calling function, cached in a
+# local variable. This is commonly known optimization for overly dynamic
+# languages (the idea is to cut on symbolic look up overhead, as local
+# variables are accessed by offset, not by name)
+import bench
+
+def f(x):
+    return x + 1
+
+def test(num):
+    f_ = f
+    for i in iter(range(num)):
+        a = f_(i)
+
+bench.run(test)