I recently discovered that the md_apply_fix function in the Xtensa
port of GAS has been failing to "apply" any value at all for
XTENSA_PLT relocations, leading to uninitialized data in the output.
This shows up clearly with valgrind but is apparently harmless in
many cases, perhaps because the data is usually zero. It did cause
one real failure for a program in the GCC testsuite. The patch
changes the function to always set the value to something, with a
default of zero. Tested and committed on the mainline.