Autotools: Simplify expat.pc templating (now that we can)

expat/configure.ac

@@ -394,9 +394,6 @@ AC_SUBST([AM_CFLAGS])
 AC_SUBST([AM_CXXFLAGS])
 AC_SUBST([AM_LDFLAGS])
 
-dnl updating _EXPAT_LIBRARY_NAME variable to effect the package name in expat.pc file (issues #361 and #495)
-AC_SUBST(_EXPAT_LIBRARY_NAME, ["$PACKAGE_NAME"])
-
 AS_CASE("${host_os}",
   [darwin*], [CMAKE_NOCONFIG_SOURCE=cmake/autotools/expat-noconfig__macos.cmake.in],
   [mingw*], [CMAKE_NOCONFIG_SOURCE=cmake/autotools/expat-noconfig__windows.cmake.in],

expat/expat.pc.in

@@ -3,9 +3,9 @@ exec_prefix=@exec_prefix@
 libdir=@libdir@
 includedir=@includedir@
 
-Name: @_EXPAT_LIBRARY_NAME@
+Name: @PACKAGE_NAME@
 Version: @PACKAGE_VERSION@
 Description: expat XML parser
 URL: https://libexpat.github.io/
-Libs: -L${libdir} -l@_EXPAT_LIBRARY_NAME@
+Libs: -L${libdir} -l@PACKAGE_NAME@
 Cflags: -I${includedir}