SECTION(symbol) returns the name of a symbol's section (#1066)

Fixes #963

Co-authored-by: Eldred Habert <eldredhabert0@gmail.com>

test/asm/long-section-name.asm

@@ -0,0 +1,2 @@
+SECTION "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit", ROM0[0]
+println "This is section ", SECTION(@)

test/asm/long-section-name.err

@@ -0,0 +1,2 @@
+warning: long-section-name.asm(1): [-Wlong-string]
+    String constant too long

test/asm/long-section-name.out

@@ -0,0 +1 @@
+This is section Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor i

test/asm/section-name-invalid.asm

@@ -0,0 +1,7 @@
+SECTION "test", ROM0
+
+Label:
+println SECTION(Label) ; OK
+
+DEF Value EQU 42
+println SECTION(Value) ; not OK

test/asm/section-name-invalid.err

@@ -0,0 +1,2 @@
+FATAL: section-name-invalid.asm(7):
+    "Value" does not belong to any section

test/asm/section-name-invalid.out

@@ -0,0 +1 @@
+test

test/asm/section-name.asm

@@ -0,0 +1,19 @@
+SECTION "aaa", ROM0[5]
+	println SECTION(@)
+	Label1: println SECTION(Label1)
+	dw STARTOF(SECTION(@))
+
+SECTION UNION "bbb", WRAM0
+	println SECTION(@)
+	Label2:
+	.local1: println SECTION(Label2.local1)
+	.local2: println SECTION(.local2)
+
+SECTION FRAGMENT "ccc", HRAM
+	println SECTION(@)
+	: println SECTION(:-)
+
+	PUSHS
+	SECTION "ddd", ROMX
+		println SECTION(@)
+	POPS

test/asm/section-name.out

@@ -0,0 +1,8 @@
+aaa
+aaa
+bbb
+bbb
+bbb
+ccc
+ccc
+ddd