MarioUtil/DrawUtil: fix silhouette alpha and texture translation

[gitRasheed]

TSilhouette::perform takes the sun alpha from unk18 and translates the texture matrix by 0.5, as the target does; the fabricated getUnk1CAlpha goes.

[decomp-dev]

Report for GMSJ01 (2749193 - ce87ba3)

📈 1 improvement in an unmatched item

Unit	Item	Bytes	Before	After
mario/MarioUtil/DrawUtil	TSilhouette::perform(unsigned long, JDrama::TGraphics*)	0	99.83%	99.84%

📉 1 regression in an unmatched item

Unit	Item	Bytes	Before	After
mario/MarioUtil/DrawUtil	.sdata2	-2	96.15%	94.23%

---

Report for GMSP01 (2749193 - ce87ba3)

📈 1 improvement in an unmatched item

Unit	Item	Bytes	Before	After
mario/MarioUtil/DrawUtil	TSilhouette::perform(unsigned long, JDrama::TGraphics*)	0	99.83%	99.84%

📉 1 regression in an unmatched item

Unit	Item	Bytes	Before	After
mario/MarioUtil/DrawUtil	.sdata2	-2	96.15%	94.23%