ctx,st3m: increment the frame-clock of the texture cache context

All the contexts share the texture and eid handling of the "master" ctx context, which is within the rasterizer of the rendering context for framebuffer 0. For the age-tracking to work right we need to have a logical clock tied to the use of textures, this adds a small convenience function to the ctx implementation to inject an appropriate increment of this clock per rendered frame. This makes the ejection policy of discarding a least frequently used eid, which works well with eids created on demand and cached by an identity.

components/ctx/ctx_config.h

@@ -56,7 +56,7 @@
 #define CTX_ENABLE_SHADOW_BLUR  0
 #define CTX_FONTS_FROM_FILE     0
 #define CTX_MAX_KEYDB          16
-#define CTX_MAX_TEXTURES        16
+#define CTX_MAX_TEXTURES        32
 #define CTX_PARSER_MAXLEN       512
 #define CTX_PARSER_FIXED_TEMP   1
 #define CTX_CURRENT_PATH        1