[RFC, PATCH, MIPS] Add support for O32 FPXX and program header based ABI information

[Joseph S. Myers]

We don't want to introduce new internal interfaces using #ifdef, because 
of the risk of typos being undetected.  Thus, ELF_MACHINE_NEEDS_PHDR_CHECK 
should be a macro that all architectures define to either 0 or 1, tested 
with #if not #ifdef.  Or, even better, have most architectures define a 
dummy version of elf_machine_phdr_check to which the call just gets 
optimized out, so no conditional code is needed in dl-load.c at all.

We don't want to introduce new uses of __builtin_expect; use 
__glibc_likely / __glibc_unlikely instead.

To avoid -Wundef warnings, and in line with the principle about avoiding 
#ifdef interfaces, make HAVE_MIPS_MODULE_FPXX_DIRECTIVE a 1/0 macro rather 
than a defined/undefined one.  (Right now you have it defined/undefined 
but also test with #if, leading to warnings in the undefined case.)

-- 
Joseph S. Myers
joseph@codesourcery.com