https://bugs.gentoo.org/949813
https://sourceforge.net/p/gpsim/bugs/296/
--- ./configure.ac.orig	2025-02-17 13:47:15.764170851 +0100
+++ ./configure.ac	2025-02-17 13:47:52.610171559 +0100
@@ -167,6 +167,7 @@
   echo linking with gtk-$GTK_VERSION_T
   AC_DEFINE_UNQUOTED([GTK_VERSION],"$GTK_VERSION_T",[gtk version])
 fi
+X_LDFLAGS="$X_LDFLAGS -lm"
 
 wi_LIB_READLINE
   if test "$wi_cv_lib_readline" != yes; then