kconfig: silence warning when parsing auto.conf when a symbol has changed type

When a symbol changes type from tristate to bool, and was previously set to
'm', a subsequent silentoldconfig would warn about inconsistency, such as:

    include/config/auto.conf:3014:warning: symbol value 'm' invalid for
    HOTPLUG_PCI_PCIE

Seen by Linus with the merge in aa8032b (sequence to reproduce by Michal):
    git checkout 1fe0135
    make mrproper
    make allmodconfig
    make silentoldconfig
    git checkout aa8032b
    make allmodconfig
    make silentoldconfig

Since HOTPLUG_PCI_PCIE changed from tristate to bool in aa8032b, it was
previously set to 'm' in auto.conf by the first allmodconfig+silentoldconfig,
but then was set to 'y' by the second allmodconfig. Then the second
silentoldconfig prints the warning.

The warning in this case is a spurious warning, which happens at the time
kconfig tries to detect symbols that have changed, to touch the empty
header files in include/config used for dependency-tracking by make.

Silence the warning when we read the old auto.conf file, since it is
perfectly legit that a symbol changed type since the previous call.

Thread in:
    http://marc.info/?l=linux-pci&m=137569198904000&w=2

Reported-by: Linus Torvalds <[email protected]>
Signed-off-by: "Yann E. MORIN" <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Michal Marek <[email protected]>
Cc: Thomas Petazzoni <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Yinghai Lu <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>

0 files changed, 0 insertions, 0 deletions