scripts/tags.sh: Ignore *.mod.c

CONFIG_MODVERSIONS=y results in a .mod.c for every compiled file in the
kernel. Issuing a 'make cscope' on a compiled kernel tree results in
the cscope files containing *.mod.c files.

[prarit@prarit linux]# make cscope
[prarit@prarit linux]# cat cscope.files | grep mod.c | wc -l
4807

These files are not useful for cscope and should be ignored. For example,

   #   line  filename / context / line
   1    105  arch/x86/kvm/kvm-intel.mod.c <<GLOBAL>>
             { 0x618911fc, __VMLINUX_SYMBOL_STR(numa_node) },
   2    508  drivers/block/mtip32xx/mtip32xx.h <<GLOBAL>>
             int numa_node;
   3     55  drivers/block/mtip32xx/mtip32xx.mod.c <<GLOBAL>>
             { 0x618911fc, __VMLINUX_SYMBOL_STR(numa_node) },
   4     37  drivers/cpufreq/acpi-cpufreq.mod.c <<GLOBAL>>
             { 0x618911fc, __VMLINUX_SYMBOL_STR(numa_node) },
   <snip>

Add an export to RCS_FIND_IGNORE so it can be used in scripts/tags.sh
and add explicitly ignore *.mod.c files.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/Makefile b/Makefile
index 606ef7c..2acd9dd 100644
--- a/Makefile
+++ b/Makefile
@@ -414,8 +414,9 @@
 
 # Files to ignore in find ... statements
 
-RCS_FIND_IGNORE := \( -name SCCS -o -name BitKeeper -o -name .svn -o -name CVS \
-		   -o -name .pc -o -name .hg -o -name .git \) -prune -o
+export RCS_FIND_IGNORE := \( -name SCCS -o -name BitKeeper -o -name .svn -o    \
+			  -name CVS -o -name .pc -o -name .hg -o -name .git \) \
+			  -prune -o
 export RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn \
 			 --exclude CVS --exclude .pc --exclude .hg --exclude .git