Restore the ability to build on systems with 32-bit compat when the system compiler is not clang.  clang and gcc appear to differ signficantly in their interpretation of -isystem and --sysroot.  Further work is likely required to support an external gcc.
Restore the ability to build on systems with 32-bit compat when
the system compiler is not clang.  clang and gcc appear to differ
signficantly in their interpretation of -isystem and --sysroot.  Further
work is likely required to support an external gcc.

Reported by:	andreast, fidaj@ukr.net, sergey.dyatko@gmail.com

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