Add kmemdup ...

We have kmemdup as a UBIFS specific variant, put it into the correct
header files. Instead of reimplementing it just use memdup we already
have.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: lib64: Make string functions aware of MMU configuration ...

Optimized version of memset() in memset.S if called as:

    memset(foo, 0, size)

will try to explicitly zero out data cache with:

    dc	zva, dst

which will result in Alignement Exception (DABT) if MMU is not
enabled.

For more info see:

    - C4.4.8 "DC ZVA, Data Cache Zero by VA"
    - D5.2.8 "The effects of disabling a stage of address translation"

in "ARM Architecture Reference Manual. ARMv8, for ARMv8-A architecture
profile"

In similar vein, using optimized version of memcpy() could lead to a
unaligned 16-byte write (using 'stp'), which is not allowed for
Device-nGnRnE type of memory (see D5.2.8) and would liead to
Alignement Exception.

To fix both problems expose non-optimized and optimzied versions of
the function and created a wrapper to dispatch the call to either one
based on if MMU is enabled or not.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

string: Introduce strtobool ...

We have at least two places which convert a string to a boolean type,
so create a common function for this. strtobool treats

- any positive (nonzero) number as true
- "0" as false
- "true" (case insensitive) as true
- "false" (case insensitive) as false

Every other value results in an error and the input *val is not
modified. The caller is expected to initialize *val with the correct
default before calling strtobool.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

string: Add (x)memdup ...

It's a common task to duplicate some memory. Add (x)memdup functions.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

add protection from double inclusion in string.h

add string.h