When calling native function from AOT code, current implementation is to return
back to runtime to call aot_invoke_native, which calls wasm_runtime_invoke_native
and the latter calls assembly code. We did it before as there may be pointer and
string arguments to check and convert if the native function's registered signature
has character '*' and '$'.
As the built-in native function's signatures can be gotten in compilation time, we
check the pointer/string arguments and convert them into native address in AOT
code, and then invoke the native function directly, so as to improve performance.

Fix several issues in wasm-c-api wasm_module_imports function:
1. Two of the if branches never set the module_name and name fields which are later passed as arguments to wasm_importtype_new, and eventually might cause double-free and/or use-after-free
2. Should zero module_name/name/extern_type at the start of loop iteration, and destroy their resources when failed at the end of loop iteration
2. No need to check `if (!extern_type) { continue; }`, as extern_type is converted from type and type is already checked
3. No need to wasm_importtype_vec_delete(out) when failed, as it is passed from outside and should be destroyed by outside

Update CI files:
- add another apt repository for spec test on x86-32 as some packages
  cannot be downloaded with the Github default repository
- trigger the CI file when it is modified

Since DPFPU depends on FPU, if FPU is enabled we will never enter DPFPU
branch since `ifeq (${CONFIG_ARCH_FPU}, y)` is always true.

Signed-off-by: Huang Qi <huangqi3@xiaomi.com>