bsdmake: ensure @PREFIX@ is always replaced with a path

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Formula/bsdmake.rb

@@ -21,6 +21,8 @@ class Bsdmake < Formula
   def install
     # Replace @PREFIX@ inserted by MacPorts patches
     # Use 'prefix' since this is sometimes a keg-only brew
+    # But first replace the X11 path if X11 is installed
+    inreplace 'mk/sys.mk', '@PREFIX@', MacOS::X11.prefix if MacOS::X11.installed?
     inreplace %W[mk/bsd.README
                  mk/bsd.cpu.mk
                  mk/bsd.doc.mk
@@ -28,12 +30,10 @@ class Bsdmake < Formula
                  mk/bsd.own.mk
                  mk/bsd.port.mk
                  mk/bsd.port.subdir.mk
+                 mk/sys.mk
                  pathnames.h],
                  '@PREFIX@', prefix
 
-    # X11 path shouldn't be munged
-    inreplace 'mk/sys.mk', '@PREFIX@', MacOS::X11.prefix if MacOS::X11.installed?
-
     inreplace 'mk/bsd.own.mk' do |s|
       s.gsub! '@INSTALL_USER@', `id -un`.chomp
       s.gsub! '@INSTALL_GROUP@', `id -gn`.chomp