Allocator shim explanatory error message.

base/allocator/allocator_shim_override_glibc_weak_symbols.h

Index: base/allocator/allocator_shim_override_glibc_weak_symbols.h
diff --git a/base/allocator/allocator_shim_override_glibc_weak_symbols.h b/base/allocator/allocator_shim_override_glibc_weak_symbols.h
index dda49aa38354eb0e470aff44d8f80f1c340b8bae..7949399f2efa5763b0f6efbe4b01498a2c47e90d 100644
--- a/base/allocator/allocator_shim_override_glibc_weak_symbols.h
+++ b/base/allocator/allocator_shim_override_glibc_weak_symbols.h
@@ -105,5 +105,6 @@ SHIM_ALWAYS_EXPORT int __posix_memalign(void** r, size_t a, size_t s)
 
 // Safety check.
 #if !defined(__GLIBC__)
-#error The current platform does not seem to use Glibc.
+#error The target platform does not seem to use Glibc. Disable the allocator \
+shim by setting use_experimental_allocator_shim=false in GN args.
 #endif