cmake : fix build under Windows when enable BUILD_SHARED_LIBS (#1100)

* Fix build under Windows when enable BUILD_SHARED_LIBS

* Make AVX512 test on Windows to build the shared libs

.github/workflows/build.yml

@@ -169,7 +169,7 @@ jobs:
          - build: 'avx'
            defines: '-DLLAMA_AVX2=OFF'
          - build: 'avx512'
-           defines: '-DLLAMA_AVX512=ON'
+           defines: '-DLLAMA_AVX512=ON -DBUILD_SHARED_LIBS=ON'
 
     steps:
       - name: Clone

CMakeLists.txt

@@ -201,6 +201,10 @@ endif()
 
 if (MSVC)
     add_compile_definitions(_CRT_SECURE_NO_WARNINGS)
+
+    if (BUILD_SHARED_LIBS)
+        set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS ON)
+    endif()
 endif()
 
 if (LLAMA_LTO)