[PATCH v2] .gitignore: ignore GNUmakefile

[Qu Wenruo]

I use GNUmakefile to shorten the command of "make".

E.g. for my arm64 worktree, I have a GNUmakefile with:

 export ARCH := arm64
 export LLVM := 1
 export PACMAN_PKGBASE := linux-arm64-custom
 export PACMAN_EXTRAPACKAGES :=
 export PKGEXT := .pkg.tar
 MAKEFLAGS += -j12
 include Makefile

And for my x86_64 worktree, it looks a little simpler:

 export LLVM := 1
 export PACMAN_PKGBASE := linux-custom
 export PACMAN_EXTRAPACKAGES :=
 export PKGEXT := pkg.tar
 MAKEFLAGS += -j12
 include Makefile

So at least in my case, GNUmakefile is really a shortcut to specify
extra environment variables and build flags.
Thus it should be added to gitignore.

Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
Changelog:
v2:
- Limit the GNUmakefile to the top-level directory
---
 .gitignore | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/.gitignore b/.gitignore
index 9875120ea7bd..6f018294a119 100644
--- a/.gitignore
+++ b/.gitignore
@@ -194,3 +194,6 @@ sphinx_*/
 
 # bc language scripts (not LLVM bitcode)
 !kernel/time/timeconst.bc
+
+# GNUmakefile, mostly to export extra env variables or build flags
+/GNUmakefile
-- 
2.56.0