Remove support for direct Asm.js builds

Targeting Asm.js through wasm2js is still supported

PiperOrigin-RevId: 323078976
diff --git a/src/xnnpack/allocator.h b/src/xnnpack/allocator.h
index 3194a11..05ea6d0 100644
--- a/src/xnnpack/allocator.h
+++ b/src/xnnpack/allocator.h
@@ -19,7 +19,7 @@
 #include <xnnpack/params.h>
 
 
-#if XNN_ARCH_ASMJS || XNN_ARCH_WASM
+#if XNN_ARCH_WASM
   #define XNN_ALLOCATION_ALIGNMENT 4
 #elif (XNN_ARCH_X86 || XNN_ARCH_X86_64) && !XNN_PLATFORM_MOBILE
   #define XNN_ALLOCATION_ALIGNMENT 64