abieos not linkable by C program?

src/abieos.cpp isn't included in static library.
so my simple C program can't compile/link.
```
#include
#include "../src/abieos.h"

int main() {

fprintf(stdout,"hello\n");
abieos_context *context = abieos_create();
abieos_destroy(context);
}
```

my 'fix' is to include src/abieos.cpp in the library CMakeList.txt

```
diff --git a/CMakeLists.txt b/CMakeLists.txt
index c14e851..e5efa05 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -33,7 +33,7 @@ endif()

find_package(Threads)

-add_library(abieos STATIC src/abi.cpp src/crypto.cpp include/eosio/fpconv.c)
+add_library(abieos STATIC src/abieos.cpp src/abi.cpp src/crypto.cpp include/eosio/fpconv.c)
target_include_directories(abieos PUBLIC include external/rapidjson/include)

add_library(abieos_module MODULE src/abieos.cpp src/abi.cpp src/crypto.cpp include/eosio/fpconv.c)
```