gitignore: x86_64 files

Add filters for x86_64 generated files.

Signed-off-by: Brian Gerst <bgerst@didntduck.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

arch/x86_64/boot/.gitignore

@@ -0,0 +1,3 @@
+bootsect
+bzImage
+setup

arch/x86_64/boot/tools/.gitignore

@@ -0,0 +1 @@
+build

arch/x86_64/ia32/.gitignore

@@ -0,0 +1 @@
+vsyscall*.so