internal/ops: use uint32 for pc, version, macroID

4GB of render data should be sufficient for anyone.

By replacing an int with uint32, it allows for a smaller memory
footprint and faster caching. Example impact on rendering static
labels.

                                     │  before.txt  │             after.txt              │
                                     │    sec/op    │   sec/op     vs base               │
LabelStatic/1000runes-RTL-arabic-32     98.08µ ± 3%   88.17µ ± 1%  -10.10% (p=0.002 n=6)
LabelStatic/1000runes-RTL-complex-32    103.9µ ± 2%   101.9µ ± 1%   -1.84% (p=0.009 n=6)
LabelStatic/1000runes-RTL-emoji-32      113.3µ ± 2%   100.7µ ± 3%  -11.11% (p=0.002 n=6)
LabelStatic/1000runes-RTL-latin-32     100.01µ ± 1%   92.31µ ± 1%   -7.69% (p=0.002 n=6)
LabelStatic/1000runes-LTR-arabic-32     97.90µ ± 2%   87.92µ ± 2%  -10.19% (p=0.002 n=6)
LabelStatic/1000runes-LTR-complex-32   102.63µ ± 2%   99.81µ ± 1%   -2.75% (p=0.002 n=6)
LabelStatic/1000runes-LTR-emoji-32     106.56µ ± 2%   98.47µ ± 1%   -7.59% (p=0.002 n=6)
LabelStatic/1000runes-LTR-latin-32      97.51µ ± 1%   92.60µ ± 3%   -5.03% (p=0.002 n=6)
geomean                                 102.4µ        95.09µ        -7.10%

Signed-off-by: Egon Elbre <egonelbre@gmail.com>

op/clip/clip.go

@@ -29,7 +29,7 @@ type Op struct {
 type Stack struct {
 	ops     *ops.Ops
 	id      ops.StackID
-	macroID int
+	macroID uint32
 }
 
 var pathSeed maphash.Seed

op/op.go

@@ -111,7 +111,7 @@ type TransformOp struct {
 // TransformStack represents a TransformOp pushed on the transformation stack.
 type TransformStack struct {
 	id      ops.StackID
-	macroID int
+	macroID uint32
 	ops     *ops.Ops
 }
 

op/paint/paint.go

@@ -48,7 +48,7 @@ type PaintOp struct {
 // until Pop is called.
 type OpacityStack struct {
 	id      ops.StackID
-	macroID int
+	macroID uint32
 	ops     *ops.Ops
 }