Fix aarch and android builds (#4576)

- [x] I have read and followed the [Contribution Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/CONTRIBUTING.md#code-contributions).
- [x] I have read and followed the [AI Policy](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/AI.md).
- [x] I have read and followed the [Coding Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/Coding.md) to the best of my ability.

-------------------
credit: John and Crueter

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4576
Reviewed-by: crueter <crueter@eden-emu.dev>

src/android/app/build.gradle.kts

@@ -259,7 +259,7 @@ android {
 
     externalNativeBuild {
         cmake {
-            version = "3.31.6"
+            version = "3.31.5"
             path = file("${edenDir}/CMakeLists.txt")
         }
     }

src/core/arm/nce/arm_nce_asm_definitions.h

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 /* SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project */
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
@@ -5,9 +8,22 @@
 
 #define __ASSEMBLY__
 
+// Newer Linux UAPI headers check __ASSEMBLER__ instead of __ASSEMBLY__ to hide C declarations.
+// Without it, asm-generic/signal.h redeclares sigset_t and clashes with glibc's. Only define it
+// around these includes, since glibc headers also look at __ASSEMBLER__.
+#ifndef __ASSEMBLER__
+#define __ASSEMBLER__
+#define EDEN_NCE_UNDEF_ASSEMBLER
+#endif
+
 #include <asm-generic/signal.h>
 #include <asm-generic/unistd.h>
 
+#ifdef EDEN_NCE_UNDEF_ASSEMBLER
+#undef __ASSEMBLER__
+#undef EDEN_NCE_UNDEF_ASSEMBLER
+#endif
+
 #define ReturnToRunCodeByExceptionLevelChangeSignal SIGUSR2
 #define BreakFromRunCodeSignal SIGURG
 #define GuestAccessFaultSignal SIGSEGV