cmake : enable OpenBLAS on Windows (ggerganov#1128)

Fixed the issue of not being able to find OpenBLAS on the Windows platform. Even though the name of the previously released binary file was whisper-blas-bin-x64.zip, BLAS was actually not enabled. After enabling, the inference speed can increase by 3-4 times.

CMakeLists.txt

@@ -136,22 +136,33 @@ if (WHISPER_OPENBLAS)
 endif()
 
 if (WHISPER_BLAS)
-    set(BLA_STATIC 1)
-    set(BLA_VENDOR ${WHISPER_BLAS_VENDOR})
-#    set(BLA_PREFER_PKGCONFIG 1)
-    set(BLA_SIZEOF_INTEGER 8)
-    find_package(BLAS)
-
-    if(BLAS_FOUND)
-        message(STATUS "BLAS compatible library found")
-        message(STATUS "Libraries ${BLAS_LIBRARIES}")
-        set(WHISPER_EXTRA_FLAGS ${WHISPER_EXTRA_FLAGS} -DGGML_USE_OPENBLAS)
-
-        include_directories(${BLAS_INCLUDE_DIRS})
-        set(WHISPER_EXTRA_LIBS ${WHISPER_EXTRA_LIBS} ${BLAS_LIBRARIES})
-    else()
-        message(WARNING "BLAS library was not found")
-    endif()
+    if (WIN32)
+        if(DEFINED ENV{OPENBLAS_PATH})
+            set(BLAS_LIBRARIES $ENV{OPENBLAS_PATH}/lib/libopenblas.dll.a)
+            message(STATUS "Libraries ${BLAS_LIBRARIES}")
+            set(WHISPER_EXTRA_FLAGS ${WHISPER_EXTRA_FLAGS} -DGGML_USE_OPENBLAS)
+            include_directories($ENV{OPENBLAS_PATH}/include)
+            set(WHISPER_EXTRA_LIBS ${WHISPER_EXTRA_LIBS} ${BLAS_LIBRARIES})
+        else ()
+            message(WARNING "BLAS library was not found. Environment variable OPENBLAS_PATH not defined.")
+        endif ()
+    else ()
+        set(BLA_STATIC 1)
+        set(BLA_VENDOR ${WHISPER_BLAS_VENDOR})
+        #    set(BLA_PREFER_PKGCONFIG 1)
+        set(BLA_SIZEOF_INTEGER 8)
+        find_package(BLAS)
+
+        if(BLAS_FOUND)
+            message(STATUS "BLAS compatible library found")
+            message(STATUS "Libraries ${BLAS_LIBRARIES}")
+            set(WHISPER_EXTRA_FLAGS ${WHISPER_EXTRA_FLAGS} -DGGML_USE_OPENBLAS)
+            include_directories(${BLAS_INCLUDE_DIRS})
+            set(WHISPER_EXTRA_LIBS ${WHISPER_EXTRA_LIBS} ${BLAS_LIBRARIES})
+        else()
+            message(WARNING "BLAS library was not found")
+        endif()
+    endif ()
 endif ()
 
 if (WHISPER_CUBLAS)