optimize code placement

Ensure code is placed in its most logical and efficient location to improve maintainability and performance. This includes consolidating duplicate functionality into shared headers or utility files, and moving loop-invariant conditions outside of loops.

When you encounter duplicate functions across multiple files, consider moving them to a shared header as inline functions. For example, instead of having ggml_are_same_layout duplicated in ggml-alloc.c and ggml-backend.cpp, move it to ggml.h as an inline function.

Similarly, extract conditions that don’t change within loops to outside the loop:

// Instead of:
for (size_t i = 0, n = 3; i < n; ++i) {
    if (op->src[i] != NULL && (op->src[i]->type == GGML_TYPE_BF16 || op->type == GGML_TYPE_BF16)) {
        // ...
    }
}

// Extract the loop-invariant condition:
bool op_is_bf16 = (op->type == GGML_TYPE_BF16);
for (size_t i = 0, n = 3; i < n; ++i) {
    if (op->src[i] != NULL && (op->src[i]->type == GGML_TYPE_BF16 || op_is_bf16)) {
        // ...
    }
}

This approach reduces code duplication, improves performance by avoiding redundant checks, and enhances code readability by making the logic structure clearer.