mount: fix -o user=foo mishandling, fix unc= generation, add prefixpath=

function                                             old     new   delta
singlemount                                         1019    1049     +30
packed_usage                                       29252   29257      +5
parse_mount_options                                  230     232      +2
mount_option_str                                     337     338      +1
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(add/remove: 0/0 grow/shrink: 4/0 up/down: 38/0)               Total: 38 bytes

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
fix a typo in config help text. Closes 5714

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
code shrink

function                                             old     new   delta
applet_name_compare                                   36      31      -5
find_applet_by_name                                   43      25     -18

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
ash: revert wrong "fix" for an apparent memory leak. Closes 5822

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Merge git://busybox.net/busybox