Use absolute paths in install names, not @rpath-based ones.
--- configure.orig	2024-01-09 18:25:00.000000000 -0600
+++ configure	2024-04-30 01:41:34.000000000 -0500
@@ -2843,7 +2843,7 @@
     LIBNAME="libmpdec.dylib"
     LIBSONAME="libmpdec.4.dylib"
     LIBSHARED="libmpdec.4.0.0.dylib"
-    CONFIGURE_LDFLAGS="-dynamiclib $FPIC -install_name @rpath/$LIBSONAME -compatibility_version 4.0 -current_version 4.0.0"
+    CONFIGURE_LDFLAGS="-dynamiclib $FPIC -install_name \$(libdir)/$LIBSONAME -compatibility_version 4.0 -current_version 4.0.0"
     ;;
   *-*-aix*)
     LIBNAME=
@@ -2887,7 +2887,7 @@
     LIBNAME_CXX="libmpdec++.dylib"
     LIBSONAME_CXX="libmpdec++.4.dylib"
     LIBSHARED_CXX="libmpdec++.4.0.0.dylib"
-    CONFIGURE_LDXXFLAGS="-dynamiclib $FPIC -install_name @rpath/$LIBSONAME_CXX -compatibility_version 4.0 -current_version 4.0.0"
+    CONFIGURE_LDXXFLAGS="-dynamiclib $FPIC -install_name \$(libdir)/$LIBSONAME_CXX -compatibility_version 4.0 -current_version 4.0.0"
     ;;
   *-*-aix*)
     LIBNAME_CXX=
--- libmpdec/Makefile.in.orig	2024-01-09 18:25:00.000000000 -0600
+++ libmpdec/Makefile.in	2024-04-30 01:46:37.000000000 -0500
@@ -3,6 +3,10 @@
 #                          Unix Makefile for libmpdec
 # ==============================================================================
 
+prefix = @prefix@
+exec_prefix = @exec_prefix@
+libdir = @libdir@
+
 ENABLE_STATIC = @ENABLE_STATIC@
 ENABLE_SHARED = @ENABLE_SHARED@
 ENABLE_MINGW = @ENABLE_MINGW@
--- libmpdec++/Makefile.in.orig	2024-01-09 18:25:00.000000000 -0600
+++ libmpdec++/Makefile.in	2024-04-30 01:46:24.000000000 -0500
@@ -3,6 +3,10 @@
 #                          Unix Makefile for libmpdec++
 # ==============================================================================
 
+prefix = @prefix@
+exec_prefix = @exec_prefix@
+libdir = @libdir@
+
 ENABLE_STATIC = @ENABLE_STATIC@
 ENABLE_SHARED = @ENABLE_SHARED@
 ENABLE_MINGW = @ENABLE_MINGW@