rpc : fix load/store misaligned addresses

[ggerganov]

Fix a few errors when building with LLAMA_SANITIZE_UNDEFINED=ON:

./bin/rpc-server -p 50052

Accepted client connection, free_mem=206158430208, total_mem=206158430208
/Users/ggerganov/development/github/llama.cpp/ggml-rpc.cpp:1035:32: runtime error: reference binding to misaligned address 0x000140009654 for type 'const uint64_t' (aka 'const unsigned long long'), which requires 8 byte alignment
0x000140009654: note: pointer points here
  28 10 48 6f b0 39 52 18  01 00 00 00 00 00 00 00  00 c0 80 01 00 60 00 00  00 08 00 00 02 00 00 00
              ^ 
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /Users/ggerganov/development/github/llama.cpp/ggml-rpc.cpp:1035:32 in 
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.4.sdk/usr/include/c++/v1/tuple:398:102: runtime error: reference binding to misaligned address 0x000140009654 for type 'const unsigned long long', which requires 8 byte alignment
0x000140009654: note: pointer points here
  28 10 48 6f b0 39 52 18  01 00 00 00 00 00 00 00  00 c0 80 01 00 60 00 00  00 08 00 00 02 00 00 00
              ^ 
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.4.sdk/usr/include/c++/v1/tuple:398:102 in 
/Users/ggerganov/development/github/llama.cpp/ggml-rpc.cpp:1039:39: runtime error: load of misaligned address 0x000140008004 for type 'const uint64_t' (aka 'const unsigned long long'), which requires 8 byte alignment
0x000140008004: note: pointer points here
  a5 02 00 00 b0 39 52 18  01 00 00 00 40 3b 52 18  01 00 00 00 d0 3c 52 18  01 00 00 00 80 41 52 18
              ^ 
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /Users/ggerganov/development/github/llama.cpp/ggml-rpc.cpp:1039:39 in 
Client connection closed

./bin/llama-cli -m ../models/tinyllama-1b/ggml-model-q8_0.gguf -p "Hello, my name is" --rpc 0.0.0.0:50052 -ngl 99 -n 32

llama_new_context_with_model: RPC[0.0.0.0:50052] compute buffer size =   148.00 MiB
llama_new_context_with_model:        CPU compute buffer size =     8.01 MiB
llama_new_context_with_model: graph nodes  = 710
llama_new_context_with_model: graph splits = 3
/Users/ggerganov/development/github/llama.cpp/ggml-rpc.cpp:604:9: runtime error: store to misaligned address 0x0003300c0004 for type 'uint64_t' (aka 'unsigned long long'), which requires 8 byte alignment
0x0003300c0004: note: pointer points here
  a5 02 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
              ^ 
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /Users/ggerganov/development/github/llama.cpp/ggml-rpc.cpp:604:9 in 

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