math.big: remove import math dependency (math.big only uses min/max/abs)

vlib/math/big/min_max.v

@@ -0,0 +1,26 @@
+module big
+
+[inline]
+fn imax(a int, b int) int {
+	return if a > b { a } else { b }
+}
+
+[inline]
+fn imin(a int, b int) int {
+	return if a < b { a } else { b }
+}
+
+[inline]
+fn umax(a u32, b u32) u32 {
+	return if a > b { a } else { b }
+}
+
+[inline]
+fn umin(a u32, b u32) u32 {
+	return if a < b { a } else { b }
+}
+
+[inline]
+fn iabs(v int) int {
+	return if v > 0 { v } else { -v }
+}