Duplicates between cygwin1.dll and libc.a.

[Robert Collins]

The following functions (at a minimum):

`malloc':
`free':
`realloc':
`strerror':
`setenv':
`unsetenv':
`getenv':

Are defined in both the libc source and the cygwin source. Which one is
exposed for user programs to link against, and is the second one 
A) used by cygwin internally
B) not used in the cygwin environment at all
?

The libc code all seem to be the same - they call the _foo_r version of
the same function, and there are no obvious duplicates there. I'm still
working on profiling, for those who are interested.

Rob