x86: update .gitignore entries

vdso / vsycall create .so.dbg files now.
Add *.so.dbg to the main .ignore file

Exclude the compile time created boot directory in arch/x86_64 as well
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

.gitignore

@@ -12,6 +12,7 @@
 *.s
 *.ko
 *.so
+*.so.dbg
 *.mod.c
 *.i
 *.lst

arch/x86_64/.gitignore

+boot