sokol,fontstash: move f_d_use_freetype.v to vlib/fontstash/a_d_use_freetype.v

vlib/fontstash/a_d_use_freetype.v

@@ -1,4 +1,4 @@
-module f
+module fontstash
 
 #define FONS_USE_FREETYPE
 

vlib/v/ast/ast.v

@@ -767,6 +767,7 @@ pub struct HashStmt {
 pub:
 	mod         string
 	pos         token.Position
+	source_file string
 pub mut:
 	val  string // example: 'include <openssl/rand.h> # please install openssl // comment'
 	kind string // : 'include'

vlib/v/gen/cgen.v

@@ -1165,7 +1165,7 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 					g.includes.writeln(guarded_include)
 				}
 			} else if node.kind == 'define' {
-				g.includes.writeln('// defined by module `$node.mod`:')
+				g.includes.writeln('// defined by module `$node.mod` in file `$node.source_file`:')
 				g.includes.writeln('#define $node.main')
 			}
 		}

vlib/v/parser/comptime.v

@@ -33,6 +33,7 @@ fn (mut p Parser) hash() ast.HashStmt {
 	// p.trace('a.v', 'kind: ${kind:-10s} | pos: ${pos:-45s} | hash: $val')
 	return ast.HashStmt{
 		mod: p.mod
+		source_file: p.file_name
 		val: val
 		kind: kind
 		main: main_str