//Using mongo-c-driver from master
$ gcc -o hello hello_mongoc.c $(pkg-config --cflags --libs libmongoc-static-1.0)
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-openssl.c.obj):mongoc-openssl.c:(.text+0x165): undefined reference to `__imp_CertOpenStore'
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-openssl.c.obj):mongoc-openssl.c:(.text+0x27a): undefined reference to `__imp_CertEnumCertificatesInStore'
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-openssl.c.obj):mongoc-openssl.c:(.text+0x29e): undefined reference to `__imp_CertCloseStore'
collect2.exe: error: ld returned 1 exit status

//Using mongo-c-driver version 1.6.2
$ gcc -o hello hello_mongoc.c $(pkg-config --cflags --libs libmongoc-static-1.0)
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-rpc.c.obj):mongoc-rpc.c:(.text+0x1d50): undefined reference to `bson_as_extended_json'
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-rpc.c.obj):mongoc-rpc.c:(.text+0x2364): undefined reference to `bson_as_extended_json'
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-rpc.c.obj):mongoc-rpc.c:(.text+0x23d8): undefined reference to `bson_as_extended_json'
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-rpc.c.obj):mongoc-rpc.c:(.text+0x2543): undefined reference to `bson_as_extended_json'
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-rpc.c.obj):mongoc-rpc.c:(.text+0x283b): undefined reference to `bson_as_extended_json'
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-rpc.c.obj):mongoc-rpc.c:(.text+0x28a2): more undefined references to `bson_as_extended_json' follow
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-uri.c.obj):mongoc-uri.c:(.text+0x448f): undefined reference to `bson_strcasecmp'
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-uri.c.obj):mongoc-uri.c:(.text+0x44e4): undefined reference to `bson_strcasecmp'
C:/msys64/mingw64/lib/libmongoc-static-1.0.a(mongoc-uri.c.obj):mongoc-uri.c:(.text+0x48fc): undefined reference to `bson_strcasecmp'
collect2.exe: error: ld returned 1 exit status