[fmolara]

Summary

Recognize the canonical powerpc64 and powerpc64le CPU names in the existing PowerPC configure case.

At present these hosts fall through to the unknown-architecture case, so VISUAL_ARCH_POWERPC is not defined and the existing PowerPC CPU/AltiVec detection code is not enabled. This complements the Linux AT_HWCAP implementation from #268; it does not introduce a new probe or change the SDL code.

The source change is limited to libvisual/configure.ac.

Validation

On the current upstream 0.4.x base (12bdb54397dd), with this change:

• Native amd64 build of the core library, SDL examples and lv-tool, plus an initialization/quit smoke test.
• Configure-only checks for powerpc-linux-gnu, powerpc64-linux-gnu, powerpc64le-linux-gnu, ppc64-linux-gnu and ppc64le-linux-gnu all define VISUAL_ARCH_POWERPC. These name-mapping checks use native compilers; they are not PowerPC cross-builds.

Earlier before/after testing of the same functional change against Debian's 0.4.2 source used GCC 16.2.0 and QEMU user-mode 11.1.3:

• The original libraries fail the CPU-identification assertion on both PowerPC64 targets; the patched libraries pass.
• Patched ppc64: 970 reports AltiVec present and POWER5+ reports it absent.
• Patched ppc64le: POWER8 reports AltiVec present.
• 32-bit controls: 750/G3 reports AltiVec absent and 7400 reports it present.
• In each patched run, libvisual's result agrees with getauxval(AT_HWCAP). Defined exported-symbol lists are unchanged for both 64-bit targets.

Those QEMU tests were performed on the Debian source, not rerun on the current upstream checkout, and are not real-hardware validation.

Local build caveat: a stock out-of-tree build failed in the generated PO Makefile (/config.status), and an out-of-tree retry also exposed the examples' missing generated-header include path. The native verification above used an in-tree build with explicit make top_builddir="$PWD". No build-system workaround is included in this PR.

[fmolara]

For context, the translation check fails before comparing catalogs: configure receives a literal backslash. The same failure predates this PR (1 November run). Both failing runs use Ubuntu 26.04; the 13 October run passed on Ubuntu 24.04. I am keeping this PR limited to PowerPC64 recognition.