Allow STARTOF(SECTTYPE) and SIZEOF(SECTTYPE) to be constant when possible (#2131)

test/asm/secttype-sizeof-startof-unknown.asm

@@ -0,0 +1,5 @@
+SECTION "ROM0", ROM0[STARTOF(ROM0)]
+Label:: ds SIZEOF(ROM0)
+
+SECTION "WRAM0", WRAM0[STARTOF(WRAM0)]
+wLabel:: ds SIZEOF(WRAM0)

test/asm/secttype-sizeof-startof-unknown.err

@@ -0,0 +1,5 @@
+error: Expected constant expression: Section type ROM0's size is not known (can be affected by RGBLINK '-t/--tiny')
+    at secttype-sizeof-startof-unknown.asm(2)
+error: Expected constant expression: Section type WRAM0's size is not known (can be affected by RGBLINK '-w/--wramx')
+    at secttype-sizeof-startof-unknown.asm(5)
+Assembly aborted with 2 errors

test/asm/secttype-sizeof-startof.asm

@@ -0,0 +1,13 @@
+SECTION "ROMX", ROMX[STARTOF(ROMX)], BANK[1]
+xLabel:: ds SIZEOF(ROMX), $22
+
+SECTION "VRAM", VRAM[STARTOF(VRAM)], BANK[0]
+vLabel:: ds SIZEOF(VRAM)
+
+SECTION "ROM0", ROM0[STARTOF(ROM0)]
+ASSERT !ISCONST(SIZEOF(ROM0))  ; rgblink may have -t/--tiny
+Label:: ds $4000, $11
+
+SECTION "WRAM0", WRAM0[STARTOF(WRAM0)]
+ASSERT !ISCONST(SIZEOF(WRAM0)) ; rgblink may have -w/--wramx
+wLabel:: ds $1000

test/asm/secttype-sizeof-startof.out.bin

@@ -0,0 +1 @@
+Line truncated