Add mksort implementation

Bug: 218736658
Test: ./out/rbcrun ./build/make/tests/run.rbc
Change-Id: I0069e7059453c16d299cc650f56c320d905f1958

tests/run.rbc

@@ -32,6 +32,9 @@ def assert_eq(expected, actual):
         fail("Expected '%s', got '%s'" % (expected, actual))
 
 # Unit tests for non-trivial runtime functions
+assert_eq(["a", "b", "c"], rblf.mksort("b a    c c"))
+assert_eq(["a", "b", "c"], rblf.mksort(["b", "a", "c", "c"]))
+
 assert_eq("", rblf.mkstrip(" \n \t    "))
 assert_eq("a b c", rblf.mkstrip("  a b   \n  c \t"))
 assert_eq(1, rblf.mkstrip(1))