Fix range obscurity and compile error.

Author: two-horned

lib/std/math/gcd.zig

@@ -6,12 +6,12 @@ const std = @import("../std.zig");
 pub fn gcd(a: anytype, b: anytype) @TypeOf(a, b) {
     const N = switch (@TypeOf(a, b)) {
         // convert comptime_int to some sized int type for @ctz
-        comptime_int => std.math.IntFittingRange(@min(a, b), @max(a, b)),
+        comptime_int => std.math.IntFittingRange(0, @max(a, b)),
         else => |T| T,
     };
 
     if (@typeInfo(N) != .int or @typeInfo(N).int.signedness != .unsigned) {
-        @compileError("`a` and `b` must be usigned integers");
+        @compileError("`a` and `b` must be unsigned integers");
     }
 
     // using an optimised form of Stein's algorithm: