Fix #284

[goerch]

Tested on Windows 11 with CPU-only. During compilation I see

warning D9002: Unbekannte Option "-mfma" wird ignoriert. 
warning D9002: Unbekannte Option "-mf16c" wird ignoriert.
warning D9002: Unbekannte Option "-mavx" wird ignoriert. 
warning D9002: Unbekannte Option "-mavx2" wird ignoriert.

Tests before:

    Start 1: test-vec0
1/9 Test #1: test-vec0 ........................   Passed    3.30 sec
    Start 2: test-grad0
2/9 Test #2: test-grad0 .......................   Passed    3.65 sec
    Start 3: test-opt
3/9 Test #3: test-opt .........................   Passed   62.26 sec
    Start 4: test-mul-mat0
4/9 Test #4: test-mul-mat0 ....................   Passed    7.83 sec
    Start 5: test-mul-mat2
5/9 Test #5: test-mul-mat2 ....................   Passed    2.91 sec
    Start 6: test0
6/9 Test #6: test0 ............................   Passed    0.01 sec
    Start 7: test1
7/9 Test #7: test1 ............................   Passed    0.04 sec
    Start 8: test2
8/9 Test #8: test2 ............................   Passed    0.11 sec
    Start 9: test3
9/9 Test #9: test3 ............................   Passed    0.06 sec

100% tests passed, 0 tests failed out of 9

Total Test time (real) =  80.20 sec

Tests after:

Test project C:/Users/Win10/Documents/GitHub/ggml/build
    Start 1: test-vec0
1/9 Test #1: test-vec0 ........................   Passed    3.29 sec
    Start 2: test-grad0
2/9 Test #2: test-grad0 .......................   Passed    3.58 sec
    Start 3: test-opt
3/9 Test #3: test-opt .........................   Passed   50.89 sec
    Start 4: test-mul-mat0
4/9 Test #4: test-mul-mat0 ....................   Passed    8.02 sec
    Start 5: test-mul-mat2
5/9 Test #5: test-mul-mat2 ....................   Passed    2.71 sec
    Start 6: test0
6/9 Test #6: test0 ............................   Passed    0.01 sec
    Start 7: test1
7/9 Test #7: test1 ............................   Passed    0.03 sec
    Start 8: test2
8/9 Test #8: test2 ............................   Passed    0.08 sec
    Start 9: test3
9/9 Test #9: test3 ............................   Passed    0.04 sec

100% tests passed, 0 tests failed out of 9

Total Test time (real) =  68.70 sec

Test timings are fluctuating for me.

[goerch]

Is ggml_graph_compute_thread covered by the tests? How should I check the merged version otherwise?