We trip over this every time we add a new architecture to Debian,
file_magic just does not do the right thing on Linux leading to broken
shared libraries (most particularly, GTK+) on some of the more
interesting architectures.
The only case for file_magic given (glibc <= 2.1.1 on ARM) is believed
by the ARM buildd maintainer to be an invalid one -- especially given
that the same file_magic breaks current ARM Linux. (He also points out
that, to his knowledge, the only Linux ARM distribution to ever ship
glibc <= 2.1.1 was Debian, and we stopped doing that a LONG time ago).
We've been shipping Debian libtool (both 1.4 and 1.5) with this patch
for some time, and never encountered a problem. It effectively brings
linux* to the same state as gnu* -- use pass_all for everything.
I've written the patch to keep the older code, as is done in a few other
places in the same macro, overriding with pass_all afterwards.