rsgain: fix the build after legacysupport added

audio/rsgain/Portfile

@@ -43,6 +43,9 @@ depends_lib-append              port:ffmpeg \
                                 port:libebur128 \
                                 port:taglib
 
+# https://github.com/complexlogic/rsgain/pull/140
+patchfiles-append               0001-rsgain.cpp-use-C-cmath.patch
+
 configure.args-append           -DUSE_STD_FORMAT=ON
 
 compiler.cxx_standard           2020

audio/rsgain/files/0001-rsgain.cpp-use-C-cmath.patch

@@ -0,0 +1,32 @@
+From b9611ea0679919cbc0ea241eb8b3de2d45a3b007 Mon Sep 17 00:00:00 2001
+From: Sergey Fedorov <[email protected]>
+Date: Sat, 7 Dec 2024 06:48:57 +0800
+Subject: [PATCH] rsgain.cpp: use C++ cmath
+
+---
+ src/rsgain.cpp | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git src/rsgain.cpp src/rsgain.cpp
+index 54f377f..b30ee6d 100644
+--- src/rsgain.cpp
++++ src/rsgain.cpp
+@@ -33,8 +33,8 @@
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <string.h>
+-#include <math.h>
+ #include <getopt.h>
++#include <cmath>
+ #include <string>
+ #include <locale>
+
+@@ -150,7 +150,7 @@ bool parse_max_peak_level(const char *value, double &peak)
+ {
+     char *rest = nullptr;
+     double max_peak = strtod(value, &rest);
+-    if (rest == value || !isfinite(max_peak)) {
++    if (rest == value || !std::isfinite(max_peak)) {
+         output_error("Invalid max peak level '{}'", value);
+         return false;
+     }