vbfnlo: use patch method and filter_file instead of patch directive (#28506)

* Patch only for @3.0.0beta5

* Replace version specific patch file with patch function

Co-authored-by: root <root@hahansencs8.cern.ch>

var/spack/repos/builtin/packages/vbfnlo/package.py

@@ -30,7 +30,6 @@ class Vbfnlo(AutotoolsPackage):
     # See https://github.com/vbfnlo/vbfnlo/issues/2
     variant('doc', default=False,
             description='Build documentation')
-    patch('vbfnlo_no_docs.patch', when='~doc')
 
     depends_on('hepmc')
     depends_on('gsl')
@@ -53,3 +52,7 @@ def configure_args(self):
                 "FCFLAGS=-std=legacy"]
 
         return args
+
+    @when('@3.0.0beta3:~doc')
+    def patch(self):
+        filter_file("lib src doc", "lib src", "Makefile.am")

var/spack/repos/builtin/packages/vbfnlo/vbfnlo_no_docs.patch

@@ -1,13 +0,0 @@
-diff --git a/Makefile.am b/Makefile.am
-index e3cfec3..ebf48f4 100644
---- a/Makefile.am
-+++ b/Makefile.am
-@@ -5,7 +5,7 @@ SUBDIRS = include \
-           loops \
-           amplitudes \
-           phasespace \
--          lib src doc \
-+          lib src \
-           regress
- 
- ACLOCAL_AMFLAGS = -I m4