cmake : fix "amd64" processor string (#2638)

Author: ggerganov

ggml/src/ggml-cpu/CMakeLists.txt

@@ -175,7 +175,7 @@ function(ggml_add_cpu_backend_variant_impl tag_name)
         endif()
     elseif (CMAKE_OSX_ARCHITECTURES STREQUAL "x86_64" OR CMAKE_GENERATOR_PLATFORM_LWR MATCHES "^(x86_64|i686|amd64|x64|win32)$" OR
             (NOT CMAKE_OSX_ARCHITECTURES AND NOT CMAKE_GENERATOR_PLATFORM_LWR AND
-            CMAKE_SYSTEM_PROCESSOR MATCHES "^(x86_64|i686|AMD64)$"))
+            CMAKE_SYSTEM_PROCESSOR MATCHES "^(x86_64|i686|AMD64|amd64)$"))
         if (MSVC)
             # instruction set detection for MSVC only
             if (GGML_NATIVE)