package/boost: fix patch formatting issue

Commit ea38acd17d88b9eaf853313398c772b94338ad47 ("package/boost:
backport development branch changes to fix MIPS64 build failure")
introduced a patch formatting issue detected by check-package. This
commit fixes this issue.

Fixes:

  package/boost/0001-Improve-modfunc-performance.patch:4: generate your patches with 'git format-patch -N'

  https://gitlab.com/buildroot.org/buildroot/-/jobs/3287511158

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/boost/0001-Improve-modfunc-performance.patch

@@ -1,7 +1,7 @@
 From 825aedad557b7e3bb27614335b6ced16887103de Mon Sep 17 00:00:00 2001
 From: =?UTF-8?q?Ion=20Gazta=C3=B1aga?= <igaztanaga@gmail.com>
 Date: Mon, 7 Nov 2022 00:16:44 +0100
-Subject: [PATCH 1/1] Improve "modfunc" performance Fixes #79
+Subject: [PATCH] Improve "modfunc" performance Fixes #79
  ("boost/intrusive/hashtable.hpp: build failure (undeclared indentifier)")
 
 Backport from Boost development branch to fix issues with some architectures