precompiled headers and -g

[Greg]

It appears that in order for a precompiled header (.h.gch) to be used,
it has to reside in the same directory as the source header (.h) that
it was created from.  This is somewhat cumbersome for builds that have
object files placed in a separate directory tree (as is the case with
autoconf, etc).
Given, however, that this is the behavior, here is my problem.  I would
like to compile my libraries twice, once with -g and once without.  The
object files from each build would be placed in a separate build
directories.  But what happens to precompiled headers, which would
reside in the source tree, next to their .h file?  Does a .h.gch file
need to be recompiled dependending on whether -g/-O are used?