Fix abs() ambiguity.
https://trac.macports.org/ticket/73705

--- i18n/measunit_extra.cpp.orig	2026-03-18 04:44:50
+++ i18n/measunit_extra.cpp	2026-03-23 07:51:52
@@ -33,6 +33,7 @@
 #include "util.h"
 #include <limits.h>
 #include <cstdlib>
+#include <cmath>
 U_NAMESPACE_BEGIN
 
 
@@ -686,7 +687,7 @@ class Token { (public)
         // Check if the value is integer.
         uint64_t int_result = static_cast<uint64_t>(double_result);
         const double kTolerance = 1e-9;
-        if (abs(double_result - int_result) > kTolerance) {
+        if (std::abs(double_result - int_result) > kTolerance) {
             status = kUnitIdentifierSyntaxError;
             return 0;
         }