tint/test-runner: Split expectations for FXC and DXC

Change tint's `--fxc` flag to take the path of the FXC compiler DLL.
Have tint attempt to validate with both FXC and DXC if `--validate` is
passed.

Fix the 'dirsWithNoPassExpectations' logic which looks like it got
broken with the tint -> dawn merge. It also incorrectly applied
filepath.FromSlash() on windows.

Change-Id: I0f46aa5c21bc48a2abc48402c41f846aff4a8633
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/96800
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ben Clayton <bclayton@chromium.org>

test/tint/expressions/literals/-inf.spvasm.expected.fxc.hlsl

@@ -0,0 +1,26 @@
+static float4 out_var_SV_TARGET = float4(0.0f, 0.0f, 0.0f, 0.0f);
+
+void main_1() {
+  out_var_SV_TARGET = (asfloat(0xff800000u)).xxxx;
+  return;
+}
+
+struct main_out {
+  float4 out_var_SV_TARGET_1;
+};
+struct tint_symbol {
+  float4 out_var_SV_TARGET_1 : SV_Target0;
+};
+
+main_out main_inner() {
+  main_1();
+  const main_out tint_symbol_1 = {out_var_SV_TARGET};
+  return tint_symbol_1;
+}
+
+tint_symbol main() {
+  const main_out inner_result = main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.out_var_SV_TARGET_1 = inner_result.out_var_SV_TARGET_1;
+  return wrapper_result;
+}

test/tint/expressions/literals/inf.spvasm.expected.fxc.hlsl

@@ -0,0 +1,26 @@
+static float4 out_var_SV_TARGET = float4(0.0f, 0.0f, 0.0f, 0.0f);
+
+void main_1() {
+  out_var_SV_TARGET = (asfloat(0x7f800000u)).xxxx;
+  return;
+}
+
+struct main_out {
+  float4 out_var_SV_TARGET_1;
+};
+struct tint_symbol {
+  float4 out_var_SV_TARGET_1 : SV_Target0;
+};
+
+main_out main_inner() {
+  main_1();
+  const main_out tint_symbol_1 = {out_var_SV_TARGET};
+  return tint_symbol_1;
+}
+
+tint_symbol main() {
+  const main_out inner_result = main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.out_var_SV_TARGET_1 = inner_result.out_var_SV_TARGET_1;
+  return wrapper_result;
+}

test/tint/expressions/literals/intmin.wgsl.expected.fxc.hlsl

@@ -0,0 +1,11 @@
+[numthreads(1, 1, 1)]
+void unused_entry_point() {
+  return;
+}
+
+int add_int_min_explicit() {
+  int a = -2147483648;
+  int b = (a + 1);
+  int c = (-2147483648 + 1);
+  return c;
+}

test/tint/expressions/literals/nan.spvasm.expected.fxc.hlsl

@@ -0,0 +1,26 @@
+static float4 out_var_SV_TARGET = float4(0.0f, 0.0f, 0.0f, 0.0f);
+
+void main_1() {
+  out_var_SV_TARGET = float4(asfloat(0x7fc00000u), asfloat(0x7fc00000u), asfloat(0x7fc00000u), asfloat(0x7fc00000u));
+  return;
+}
+
+struct main_out {
+  float4 out_var_SV_TARGET_1;
+};
+struct tint_symbol {
+  float4 out_var_SV_TARGET_1 : SV_Target0;
+};
+
+main_out main_inner() {
+  main_1();
+  const main_out tint_symbol_1 = {out_var_SV_TARGET};
+  return tint_symbol_1;
+}
+
+tint_symbol main() {
+  const main_out inner_result = main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.out_var_SV_TARGET_1 = inner_result.out_var_SV_TARGET_1;
+  return wrapper_result;
+}