[PATCH v4 0/5] Fix library testsuite compilation for build sysroot

["Maciej W. Rozycki" <macro@wdc.com>]

Hi,

 This is v4 of patch series, originally posted here:

<https://gcc.gnu.org/ml/gcc-patches/2019-11/msg00767.html>
<https://gcc.gnu.org/ml/gcc-patches/2019-11/msg00768.html>
<https://gcc.gnu.org/ml/gcc-patches/2019-11/msg00769.html>
<https://gcc.gnu.org/ml/gcc-patches/2019-11/msg00770.html>

v2 posted here:

<https://gcc.gnu.org/ml/gcc-patches/2020-02/msg00827.html>
<https://gcc.gnu.org/ml/gcc-patches/2020-02/msg00828.html>
<https://gcc.gnu.org/ml/gcc-patches/2020-02/msg00829.html>
<https://gcc.gnu.org/ml/gcc-patches/2020-02/msg00830.html>

and v3 posted here:

<https://gcc.gnu.org/ml/gcc-patches/2020-02/msg01592.html>
<https://gcc.gnu.org/ml/gcc-patches/2020-02/msg01593.html>
<https://gcc.gnu.org/ml/gcc-patches/2020-02/msg01594.html>
<https://gcc.gnu.org/ml/gcc-patches/2020-02/msg01595.html>

meant to address a problem with the testsuite compiler being set up across 
libatomic, libffi, libgo, libgomp with no correlation whatsoever to the 
target compiler being used in GCC compilation.  Consequently there in no 
arrangement made to set up the compilation sysroot according to the build 
sysroot specified for GCC compilation, causing a catastrophic failure 
across the testsuites affected from the inability to link executables.

 In the course of discussion it has been determined it might be the best 
if we sync with libffi rather than providing our replacement solution, as 
the upstream version has it addressed, although in a slightly messy way.  
I have therefore decided to clean it up with upstream libffi and propose a 
corresponding backport of the change to be included with our version.  
This has resulted in two patches actually, replacing 2/4 from the original 
series.  The remaining changes are the same as in v3, however Chung-Lin 
has since confirmed the libgomp change proposed here has addressed issues 
with testing in his environment (thank you, Chung-Lin!).

 Verified with a cross-compiler configured for the `riscv-linux-gnu' 
target and the `x86_64-linux-gnu' host and using RISC-V/Linux QEMU in the 
user emulation mode as the target board.  Also no change in results with 
`x86_64-linux-gnu' native regression testing.

 See individual change descriptions for details.

 I'm assuming Ian will take care of the 4/5 libgo change (Ian, it's up to 
you if you want to have it or not).

 Any objections about 1/5 previously approved by Jeff, and OK to apply 2/5 
and 3/5 (if the corresponding changes have been accepted into upstream 
libffi), as well as 5/5 to the GCC repo?

  Maciej