[PD] Externals built with MSYS2/MinGW won't load

[Christof Ressi]

Dear list, 

I tried to compile the test externals in doc/6.externs on Windows 7 from the command line using MSYS2/MinGW.
I put everything (source files, m_pd.h and pd.dll) in one folder for the sake of convenience.

I compile with 
$ gcc -c obj1.c -o obj1.o
and link with
$ ld --export-all-symbols -shared -o test-obj3.dll obj3.o pd.dll

compiling and linking works without any errors or warnings.
test-obj1 and test-obj2 seem to load and work fine in Pd, but for test-obj3 Pd console tells me:

"C:\\Program Files (x86)\\pd vanilla\\extra\\stuff\\test-obj3.dll: couldn't load"

The same thing happens when I try to build test-obj4, test-obj5 and test-dspobj~.
What could be the problem? I took the source files as they were and built all objects the exact same way...

Many thanks in advance!