Add a function call benchmark

perf/callmark.pl

@@ -0,0 +1,32 @@
+sub x1 () { } # 1
+sub x2 () { x1; x1 } # 3
+sub x3 () { x2; x2 } # 7
+sub x4 () { x3; x3 } # 15
+sub x5 () { x4; x4 } # 31
+sub x6 () { x5; x5 } # 63
+sub x7 () { x6; x6 } # 127
+sub x8 () { x7; x7 } # 255
+sub x9 () { x8; x8 } # 511
+sub x10 () { x9; x9 } # 1023
+sub x11 () { x10; x10 } # 2047
+sub x12 () { x11; x11 } # 4095
+sub x13 () { x12; x12 } # 8191
+sub x14 () { x13; x13 } # 16383
+sub x15 () { x14; x14 } # 32767
+sub x16 () { x15; x15 } # 65535
+sub x17 () { x16; x16 } # 131071
+sub x18 () { x17; x17 } # 262143
+sub x19 () { x18; x18 } # 524287
+sub x20 () { x19; x19 } # 1048575
+sub x21 () { x20; x20 } # 2097151
+sub x22 () { x21; x21 } # 4194303
+sub x23 () { x22; x22 } # 8388607
+sub x24 () { x23; x23 } # 16777215
+sub x25 () { x24; x24 } # 33554431
+sub x26 () { x25; x25 } # 67108863
+sub x27 () { x26; x26 } # 134217727
+sub x28 () { x27; x27 } # 268435455
+sub x29 () { x28; x28 } # 536870911
+sub x30 () { x29; x29 } # 1073741823
+
+x25;