Convert parser tests to filetests.

Create a new directory hierarchy under 'filetests' for all the tests
that are run by 'cton-util test'.

Convert the parser tests under 'tests/parser' to use 'test cat' and
filecheck directives.

filetests/parser/branch.cton

@@ -0,0 +1,113 @@
+; Parsing branches and jumps.
+test cat
+
+; Jumps with no arguments. The '()' empty argument list is optional.
+function minimal() {
+ebb0:
+    jump ebb1
+
+ebb1:
+    jump ebb0()
+}
+; sameln: function minimal() {
+; nextln: ebb0:
+; nextln:     jump ebb1
+; nextln: 
+; nextln: ebb1:
+; nextln:     jump ebb0
+; nextln: }
+
+; Jumps with 1 arg.
+function onearg(i32) {
+ebb0(vx0: i32):
+    jump ebb1(vx0)
+
+ebb1(vx1: i32):
+    jump ebb0(vx1)
+}
+; sameln: function onearg(i32) {
+; nextln: ebb0(vx0: i32):
+; nextln:     jump ebb1(vx0)
+; nextln: 
+; nextln: ebb1(vx1: i32):
+; nextln:     jump ebb0(vx1)
+; nextln: }
+
+; Jumps with 2 args.
+function twoargs(i32, f32) {
+ebb0(vx0: i32, vx1: f32):
+    jump ebb1(vx0, vx1)
+
+ebb1(vx2: i32, vx3: f32):
+    jump ebb0(vx2, vx3)
+}
+; sameln: function twoargs(i32, f32) {
+; nextln: ebb0(vx0: i32, vx1: f32):
+; nextln:     jump ebb1(vx0, vx1)
+; nextln: 
+; nextln: ebb1(vx2: i32, vx3: f32):
+; nextln:     jump ebb0(vx2, vx3)
+; nextln: }
+
+; Branches with no arguments. The '()' empty argument list is optional.
+function minimal(i32) {
+ebb0(vx0: i32):
+    brz vx0, ebb1
+
+ebb1:
+    brnz vx0, ebb1()
+}
+; sameln: function minimal(i32) {
+; nextln: ebb0(vx0: i32):
+; nextln:     brz vx0, ebb1
+; nextln: 
+; nextln: ebb1:
+; nextln:     brnz vx0, ebb1
+; nextln: }
+
+function twoargs(i32, f32) {
+ebb0(vx0: i32, vx1: f32):
+    brz vx0, ebb1(vx0, vx1)
+
+ebb1(vx2: i32, vx3: f32):
+    brnz vx0, ebb0(vx2, vx3)
+}
+; sameln: function twoargs(i32, f32) {
+; nextln: ebb0(vx0: i32, vx1: f32):
+; nextln:     brz vx0, ebb1(vx0, vx1)
+; nextln: 
+; nextln: ebb1(vx2: i32, vx3: f32):
+; nextln:     brnz vx0, ebb0(vx2, vx3)
+; nextln: }
+
+function jumptable(i32) {
+    jt200 = jump_table 0, 0
+    jt2 = jump_table 0, 0, ebb10, ebb40, ebb20, ebb30
+
+ebb10(v3: i32):
+    br_table v3, jt2
+    trap
+ebb20:
+    trap
+ebb30:
+    trap
+ebb40:
+    trap
+}
+; sameln: function jumptable(i32) {
+; nextln:     jt0 = jump_table 0
+; nextln:     jt1 = jump_table 0, 0, ebb0, ebb3, ebb1, ebb2
+; nextln: 
+; nextln: ebb0(vx0: i32):
+; nextln:     br_table vx0, jt1
+; nextln:     trap
+; nextln: 
+; nextln: ebb1:
+; nextln:     trap
+; nextln: 
+; nextln: ebb2:
+; nextln:     trap
+; nextln: 
+; nextln: ebb3:
+; nextln:     trap
+; nextln: }