cmake: use static build by default, fix MSVC build

Matches protobuf default behavior:
https://github.com/protocolbuffers/protobuf/tree/master/cmake#dlls-vs-static-linking

Bump min cmake version to use Protobuf_USE_STATIC_LIBS:
https://cmake.org/cmake/help/latest/module/FindProtobuf.html

build-cmake/CMakeLists.txt

@@ -4,12 +4,11 @@ SET(PACKAGE_VERSION 1.3.3)
 SET(PACKAGE_URL https://github.com/protobuf-c/protobuf-c)
 SET(PACKAGE_DESCRIPTION "Protocol Buffers implementation in C")
 
-CMAKE_MINIMUM_REQUIRED(VERSION 2.8 FATAL_ERROR)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.10 FATAL_ERROR)
 
 PROJECT(protobuf-c)
 
 #options
-option(MSVC_STATIC_BUILD "MSVC_STATIC_BUILD" OFF)
 option(BUILD_PROTO3 "BUILD_PROTO3" ON)
 option(BUILD_PROTOC "Build protoc-gen-c" ON)
 if(CMAKE_BUILD_TYPE MATCHES Debug)
@@ -28,6 +27,10 @@ if (${WORDS_BIGENDIAN})
 	ADD_DEFINITIONS(-DWORDS_BIGENDIAN)
 endif()
 
+IF (MSVC AND BUILD_SHARED_LIBS)
+	ADD_DEFINITIONS(-DPROTOBUF_C_USE_SHARED_LIB)
+ENDIF (MSVC AND BUILD_SHARED_LIBS)
+
 if(MSVC)
   # using Visual Studio C++
   SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /wd4267 /wd4244")
@@ -45,6 +48,9 @@ SET (PC_SOURCES
 
 ADD_LIBRARY(protobuf-c ${PC_SOURCES})
 set_target_properties(protobuf-c PROPERTIES COMPILE_PDB_NAME protobuf-c)
+IF (MSVC AND BUILD_SHARED_LIBS)
+	TARGET_COMPILE_DEFINITIONS(protobuf-c PRIVATE -DPROTOBUF_C_EXPORT)
+ENDIF (MSVC AND BUILD_SHARED_LIBS)
 
 INCLUDE_DIRECTORIES(${MAIN_DIR})
 INCLUDE_DIRECTORIES(${MAIN_DIR}/protobuf-c)
@@ -52,6 +58,10 @@ INCLUDE_DIRECTORIES(${MAIN_DIR}/protobuf-c)
 IF(BUILD_PROTOC)
 INCLUDE_DIRECTORIES(${CMAKE_BINARY_DIR}) # for generated files
 
+if (MSVC AND NOT BUILD_SHARED_LIBS)
+	SET(Protobuf_USE_STATIC_LIBS ON)
+endif (MSVC AND NOT BUILD_SHARED_LIBS)
+
 FIND_PACKAGE(Protobuf REQUIRED)
 INCLUDE_DIRECTORIES(${PROTOBUF_INCLUDE_DIR})
 
@@ -60,7 +70,7 @@ if (BUILD_PROTO3)
 endif()
 ENDIF()
 
-if (MSVC AND MSVC_STATIC_BUILD)
+if (MSVC AND NOT BUILD_SHARED_LIBS)
 	# In case we are building static libraries, link also the runtime library statically
 	# so that MSVCR*.DLL is not required at runtime.
 	# https://msdn.microsoft.com/en-us/library/2kzt1wy3.aspx
@@ -75,7 +85,7 @@ if (MSVC AND MSVC_STATIC_BUILD)
 		string(REGEX REPLACE "/MD" "/MT" ${flag_var} "${${flag_var}}")
 	  endif(${flag_var} MATCHES "/MD")
 	endforeach(flag_var)
-endif (MSVC AND MSVC_STATIC_BUILD)
+endif (MSVC AND NOT BUILD_SHARED_LIBS)
 
 IF(BUILD_PROTOC)
 SET(CMAKE_CXX_STANDARD 11)
@@ -86,6 +96,13 @@ ADD_EXECUTABLE(protoc-gen-c ${PROTOC_GEN_C_SRC})
 
 TARGET_LINK_LIBRARIES(protoc-gen-c ${PROTOBUF_PROTOC_LIBRARY} ${PROTOBUF_LIBRARY})
 
+IF (MSVC AND BUILD_SHARED_LIBS)
+	TARGET_COMPILE_DEFINITIONS(protoc-gen-c PRIVATE -DPROTOBUF_USE_DLLS)
+	GET_FILENAME_COMPONENT(PROTOBUF_DLL_DIR ${PROTOBUF_PROTOC_EXECUTABLE} DIRECTORY)
+	FILE(GLOB PROTOBUF_DLLS ${PROTOBUF_DLL_DIR}/*.dll)
+	FILE(COPY ${PROTOBUF_DLLS} DESTINATION ${CMAKE_BINARY_DIR})
+ENDIF (MSVC AND BUILD_SHARED_LIBS)
+
 IF(CMAKE_HOST_UNIX)
 ADD_CUSTOM_COMMAND(TARGET ${PROJECT_NAME} POST_BUILD
                    COMMAND ln -sf protoc-gen-c protoc-c
@@ -117,6 +134,9 @@ GENERATE_TEST_SOURCES(${TEST_DIR}/test-full.proto t/test-full.pb-c.c t/test-full
 
 ADD_EXECUTABLE(cxx-generate-packed-data ${TEST_DIR}/generated-code2/cxx-generate-packed-data.cc t/test-full.pb.h t/test-full.pb.cc)
 TARGET_LINK_LIBRARIES(cxx-generate-packed-data ${PROTOBUF_LIBRARY})
+IF (MSVC AND BUILD_SHARED_LIBS)
+	TARGET_COMPILE_DEFINITIONS(cxx-generate-packed-data PRIVATE -DPROTOBUF_USE_DLLS)
+ENDIF (MSVC AND BUILD_SHARED_LIBS)
 
 FILE(MAKE_DIRECTORY ${CMAKE_BINARY_DIR}/t/generated-code2)
 ADD_CUSTOM_COMMAND(OUTPUT t/generated-code2/test-full-cxx-output.inc
@@ -161,7 +181,7 @@ ENDIF()
 INSTALL(TARGETS protoc-gen-c RUNTIME DESTINATION bin)
 ENDIF() # BUILD_PROTOC
 
-INSTALL(TARGETS protobuf-c LIBRARY DESTINATION lib ARCHIVE DESTINATION lib)
+INSTALL(TARGETS protobuf-c LIBRARY DESTINATION lib ARCHIVE DESTINATION lib RUNTIME DESTINATION bin)
 INSTALL(FILES ${MAIN_DIR}/protobuf-c/protobuf-c.h DESTINATION include/protobuf-c)
 INSTALL(FILES ${MAIN_DIR}/protobuf-c/protobuf-c.h DESTINATION include)
 INSTALL(FILES ${CMAKE_BINARY_DIR}/protobuf-c.pdb DESTINATION lib OPTIONAL)