fix(ggml-cuda): HIP nodiscard + MUSA cudaMemcpyToSymbol alias

Two CI build failures both pre-existing on TQ tip, exposed by upstream-policy
CI on PR TheTom#146:

1. ubuntu-22-hip-quality-check — fattn-common.cuh:1312-1313 in TQ's HIP
   hip_f16_alloc destructor calls hipStreamSynchronize / hipFree without
   consuming the return value. HIP's recent runtime declares these
   [[nodiscard]] and the HIP quality build uses -Werror:

   error: ignoring return value of type 'hipError_t' declared with 'nodiscard'
   attribute [-Werror,-Wunused-value]

   Fix: (void) cast both calls. We're in a destructor and can't propagate
   errors anyway; intent is fire-and-forget cleanup. Matches the idiom used
   in upstream code for the same situation.

2. ubuntu-22-musa — turbo-quant.cuh uses cudaMemcpyToSymbol in InnerQ
   calibration; MUSA's vendor header (vendors/musa.h) aliases every other
   cudaMemcpy* variant but missed cudaMemcpyToSymbol. Result on MUSA build:

   error: use of undeclared identifier 'cudaMemcpyToSymbol'; did you mean
   'musaMemcpyToSymbol'?

   Fix: add the missing alias next to the other cudaMemcpy* defines.
   Mirrors the same alias already present in vendors/hip.h:143.

Both are TQ-only paths (HIP f16 alloc was added in 0757ff4 2026-04-18;
MUSA was never built against TQ in-tree). M5 Max + M2 mini local Metal
builds unaffected by either change.

Flagged by @pacak on PR TheTom#146 (ubuntu-latest-cuda + cross-vendor CI fails).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-Authored-By: tturney@psyguard.ai

Author: 2 people

ggml/src/ggml-cuda/fattn-common.cuh

@@ -1309,8 +1309,10 @@ void launch_fattn(
         hip_f16_alloc(cudaStream_t s) : stream(s) {}
         ~hip_f16_alloc() {
             if (ptr) {
-                cudaStreamSynchronize(stream);
-                cudaFree(ptr);
+                // Cast to void: hipStreamSynchronize / hipFree are [[nodiscard]] under
+                // HIP's -Werror policy; we're in a destructor and can't propagate errors.
+                (void) cudaStreamSynchronize(stream);
+                (void) cudaFree(ptr);
             }
         }
         void alloc(size_t nelements) {

ggml/src/ggml-cuda/vendors/musa.h

@@ -77,6 +77,7 @@
 #define cudaMemcpyDeviceToHost musaMemcpyDeviceToHost
 #define cudaMemcpyHostToDevice musaMemcpyHostToDevice
 #define cudaMemcpyKind musaMemcpyKind
+#define cudaMemcpyToSymbol musaMemcpyToSymbol
 #define cudaMemset musaMemset
 #define cudaMemsetAsync musaMemsetAsync
 #define cudaMemGetInfo musaMemGetInfo