Make gcc 7.5.0 available on arm32 machines

[sxa]

Currently fails to build as it can't find sys/cdefs.h on the arm32 distributions (on raspbian or Ubuntu). Possibly expecting it to be in the location it's supplied in on the RHEL machines. I had a first attempt at overriding it with the configure parameters but that didn't succeed. Breaking this out to a separate work item so it doesn't impact closing issues related to the ansible scripts on Milestone A

[sxa]

Probably worth trying this with the new 7.5.0 release on Linux/arm32 (armv7l)

[Haroon-Khel]

As anticipated, the sys/cdefs.h error occurs. Will investigate

/usr/include/features.h:367:12: fatal error: sys/cdefs.h: No such file or directory

[sxa]

Can you try adding --includedir=/usr/include/arm-linux-gnueabihf to the ./configure parameters: https://github.com/AdoptOpenJDK/openjdk-infrastructure/issues/438#issuecomment-414434025`

[Haroon-Khel]

@sxa555 That didn't work either. I tried something similar by including that directory using

export CFLAGS=-I/usr/include/arm-linux-gnueabihf
export CXXFLAGS=-I/usr/include/arm-linux-gnueabihf 

but this gave the following error
/usr/include/arm-linux-gnueabihf/gnu/stubs.h:7:11: fatal error: gnu/stubs-soft.h: No such file or directory Different to the original error, but not helpful.

Another proposed solution is to install the package g++-multilib, though I cannot find this in the apt repositories

[sxa]

-mfloat-hard on configure resolves the above issue and is the default that we use so should be ok. I've built it on the Ubuntu machines and I'll get it deployed onto the build machines and trigger runs with it so to verify it's safe to use in the nightlies for Sunday evening

For complete reference my configure line with gcc 7.5.0 was:

./configure --prefix=/usr/local/gcc --program-suffix=-7.5 --with-float=hard

[sxa]

Thought I'd closed this. Deployed and working and also enabled for JDK in adoptium/temurin-build#1968 to fix support issue 33