kbuild: export-type enhancement to modpost.c

This patch provides the ability to identify the export-type of each
exported symbols in Module.symvers.

NOTE: It updates the Module.symvers file with the additional
information as shown below.

0x0f8b92af      platform_device_add_resources   vmlinux EXPORT_SYMBOL_GPL
0xcf7efb2a      ethtool_op_set_tx_csum          vmlinux EXPORT_SYMBOL

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Avantika Mathur <mathur@us.ibm.com>
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>