get rid of generic instances of asm/exec.h

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/microblaze/include/asm/Kbuild b/arch/microblaze/include/asm/Kbuild
index db5294c..5a0e72bf 100644
--- a/arch/microblaze/include/asm/Kbuild
+++ b/arch/microblaze/include/asm/Kbuild
@@ -1,3 +1,4 @@
 include include/asm-generic/Kbuild.asm
 
 header-y  += elf.h
+generic-y += exec.h