Fix countGrapheme wiring; Reorganize zig builtins; Streamline how we export zig function

compiler/builtins/bitcode/src/num.zig

@@ -0,0 +1,22 @@
+const std = @import("std");
+const math = std.math;
+
+pub fn atan(num: f64) callconv(.C) f64 {
+    return math.atan(num);
+}
+
+pub fn isFinite(num: f64) callconv(.C) bool {
+    return math.isFinite(num);
+}
+
+pub fn powInt(base: i64, exp: i64) callconv(.C) i64 {
+    return math.pow(i64, base, exp);
+}
+
+pub fn acos(num: f64) callconv(.C) f64 {
+    return math.acos(num);
+}
+
+pub fn asin(num: f64) callconv(.C) f64 {
+    return math.asin(num);
+}