Build static or shared libraries for all platforms (#208)

Allow building static or shared libraries for all platforms instead of hardcoding this option in the cmake file. Allows the client to choose the configuration based on the value of the standard CMake option BUILD_SHARED_LIBS.

Author: planetmarshall

contrib/CMakeLists.txt

@@ -47,12 +47,8 @@ list(APPEND gemmlowp_test_headers ${gemmlowp_headers})
 file(GLOB fixedpoint_private_headers "${gemmlowp_src}/fixedpoint/*.h")
 list(APPEND fixedpoint_private_headers "${gemmlowp_src}/internal/common.h")
 
-# Eight bit int gemm library
-if(WIN32)
-    add_library(eight_bit_int_gemm STATIC ${eight_bit_int_gemm_sources_with_no_headers})
-else()
-    add_library(eight_bit_int_gemm SHARED ${eight_bit_int_gemm_sources_with_no_headers})
-endif()
+add_library(eight_bit_int_gemm ${eight_bit_int_gemm_sources_with_no_headers})
+set_target_properties(eight_bit_int_gemm PROPERTIES WINDOWS_EXPORT_ALL_SYMBOLS ON)
 target_link_libraries(eight_bit_int_gemm ${EXTERNAL_LIBRARIES})
 
 # INTERFACE target to help header include