ggml: enable PowerPC backend variants on AIX (#25983)

* ggml: enable PowerPC backend variants on AIX

Allow the PowerPC CPU backend variants to be built on AIX by extending the platform check in the CMake configuration. This reuses the existing PowerPC backend implementations without changing their behavior.

Also fix a missing semicolon in the PowerPC Q0 matmul implementation.

* Fix missing semicolon in sgemm.cpp

ggml/src/CMakeLists.txt

@@ -430,7 +430,7 @@ if (GGML_CPU_ALL_VARIANTS)
             message(FATAL_ERROR "Unsupported ARM target OS: ${CMAKE_SYSTEM_NAME}")
         endif()
     elseif (GGML_SYSTEM_ARCH STREQUAL "PowerPC")
-        if (CMAKE_SYSTEM_NAME MATCHES "Linux")
+        if (CMAKE_SYSTEM_NAME MATCHES "Linux|AIX")
             ggml_add_cpu_backend_variant(power0)
             ggml_add_cpu_backend_variant(power7_1       POWER7)
             ggml_add_cpu_backend_variant(power7_2       POWER7  VSX)

ggml/src/ggml-cpu/llamafile/sgemm.cpp

@@ -2329,7 +2329,7 @@ class tinyBLAS_Q0_PPC {
         mc = 32;
         nc = 32;
         kc = 32;
-        n_chunk = 32
+        n_chunk = 32;
     #endif
         int64_t n_aligned = 0;
         if (n % n_chunk == 0) {