Minor optimization for paint systems, initialize the paint curve before

the stroke and skip checking for initialization each time we request the
curve value.

source/blender/blenkernel/intern/brush.c

@@ -951,7 +951,6 @@ float BKE_brush_curve_strength_clamp(Brush *br, float p, const float len)
 	if (p >= len) return 0;
 	else p = p / len;
 
-	curvemapping_initialize(br->curve);
 	strength = curvemapping_evaluateF(br->curve, 0, p);
 
 	CLAMP(strength, 0.0f, 1.0f);
@@ -967,7 +966,6 @@ float BKE_brush_curve_strength(Brush *br, float p, const float len)
 	else
 		p = p / len;
 
-	curvemapping_initialize(br->curve);
 	return curvemapping_evaluateF(br->curve, 0, p);
 }
 

source/blender/editors/sculpt_paint/paint_image_proj.c

@@ -4279,9 +4279,6 @@ void *paint_proj_new_stroke(bContext *C, Object *ob, const float mouse[2], int m
 		return ps;
 	}
 
-	/* needed so multiple threads don't try to initialize the brush at once (can leak memory) */
-	curvemapping_initialize(ps->brush->curve);
-
 	paint_brush_init_tex(ps->brush);
 
 	ps->source = PROJ_SRC_VIEW;

source/blender/editors/sculpt_paint/paint_stroke.c

@@ -46,6 +46,7 @@
 #include "BKE_context.h"
 #include "BKE_paint.h"
 #include "BKE_brush.h"
+#include "BKE_colortools.h"
 
 #include "WM_api.h"
 #include "WM_types.h"
@@ -477,6 +478,9 @@ PaintStroke *paint_stroke_new(bContext *C,
 	stroke->redraw = redraw;
 	stroke->done = done;
 	stroke->event_type = event_type; /* for modal, return event */
+
+	/* initialize here to avoid initialization conflict with threaded strokes */
+	curvemapping_initialize(br->curve);
 	
 	BKE_paint_set_overlay_override(br->overlay_flags);