stage2 tests: remove unused vars

lib/std/debug.zig

@@ -896,7 +896,6 @@ fn printLineFromFileAnyOs(out_stream: anytype, line_info: LineInfo) !void {
     var buf: [mem.page_size]u8 = undefined;
     var line: usize = 1;
     var column: usize = 1;
-    var abs_index: usize = 0;
     while (true) {
         const amt_read = try f.read(buf[0..]);
         const slice = buf[0..amt_read];

lib/std/pdb.zig

@@ -590,7 +590,8 @@ pub const Pdb = struct {
 
         var sect_cont_offset: usize = 0;
         if (section_contrib_size != 0) {
-            const version = reader.readEnum(SectionContrSubstreamVersion, .Little) catch |err| switch (err) {
+            // the version
+            _ = reader.readEnum(SectionContrSubstreamVersion, .Little) catch |err| switch (err) {
                 error.InvalidValue => return error.InvalidDebugInfo,
                 else => |e| return e,
             };
@@ -616,7 +617,8 @@ pub const Pdb = struct {
 
         // Parse the InfoStreamHeader.
         const version = try reader.readIntLittle(u32);
-        const signature = try reader.readIntLittle(u32);
+        // The signature
+        _ = try reader.readIntLittle(u32);
         const age = try reader.readIntLittle(u32);
         const guid = try reader.readBytesNoEof(16);
 

lib/std/zig/parse.zig

@@ -1005,7 +1005,7 @@ const Parser = struct {
                 },
             });
         };
-        const else_payload = try p.parsePayload();
+        _ = try p.parsePayload();
         const else_expr = try p.expectStatement();
         return p.addNode(.{
             .tag = .@"if",
@@ -1189,7 +1189,7 @@ const Parser = struct {
                 });
             }
         };
-        const else_payload = try p.parsePayload();
+        _ = try p.parsePayload();
         const else_expr = try p.expectStatement();
         return p.addNode(.{
             .tag = .@"while",