[Bug target/65810] powerpc64 alignment of r2 insufficient for loading long-double constants

[amodra at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65810

--- Comment #6 from Alan Modra <amodra at gmail dot com> ---
It isn't seen most of the time because the failure happens only when r2 isn't
16-byte aligned (50% chance) and the r2 offset to a long double constant is
n*64k+32k-8 (0.012% chance per long double).  libgfortran stores paths for
error messages in .rodata, so source path can affect placement of those long
double constants.  I'm just lucky.