Suppress compiler warnings

These warnings were detected with clang version 12.0.0.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>

src/virgl_util.c

@@ -81,6 +81,7 @@ int create_eventfd(unsigned int initval)
 #ifdef HAVE_EVENTFD_H
    return eventfd(initval, EFD_CLOEXEC | EFD_NONBLOCK);
 #else
+   (void)initval;
    return -1;
 #endif
 }

src/vrend_renderer.c

@@ -825,11 +825,13 @@ static inline bool vrend_format_can_scanout(enum virgl_formats format)
 #endif
 }
 
+#ifdef ENABLE_MINIGBM_ALLOCATION
 static inline bool vrend_format_can_texture_view(enum virgl_formats format)
 {
    return has_feature(feat_texture_view) &&
       tex_conv_table[format].flags & VIRGL_TEXTURE_CAN_TEXTURE_STORAGE;
 }
+#endif
 
 struct vrend_context_tweaks *vrend_get_context_tweaks(struct vrend_context *ctx)
 {

src/vrend_winsys.c

@@ -230,4 +230,4 @@ bool vrend_winsys_different_gpu(void)
       return virgl_egl_different_gpu(egl);
 #endif
    return false;
-}
+}

vtest/vtest_shm.c

@@ -38,6 +38,8 @@ static int memfd_create(const char *name, unsigned int flags)
 #ifdef __NR_memfd_create
     return syscall(__NR_memfd_create, name, flags);
 #else
+    (void)name;
+    (void)flags;
     return -1;
 #endif
 }