Remove support for the -no-checking flag (#392)

* Remove support for the -no-checking flag

Fixes #381
Fixes #383
Work on #382

- No longer expose flag through API (`SLANG_COMPILE_FLAG_NO_CHECKING`) and command-line (`-no-checking`) options

- Remove all logic in `check.cpp` that was withholding diagnostics (including errors) when the no-checking mode was enabled

- Remove `HiddenImplicitCastExpr`, which was only created to support no-checking mode (it represented an implicit cast that our checking through was needed, but couldn't emit because it might be wrong)

- Remove logic for storing function bodies as raw token lists when checking is turned off. I'm leaving in the `UnparsedStmt` AST node in case we ever need/want to lazily parse and check function bodies down the line.

- Remove a few of the code-generation paths we had to contend with, but keep the comment about them in place.

- Remove GLSL-based tests that can't meaningfully work with the new approach.

- Fix other tests that used a GLSL baseline so that their GLSL compiles with `-pass-through glslang` instead of invoking `slang` with the `-no-checking` flag.

- Remove tests that were explicitly added to test the "rewriter + IR" path, since that is no longer supported.

There is more cleanup that can be done here, now that we know that AST-based rewrite and IR will never co-exist, but it is probably easier to deal with that as part of removing the AST-based rewrite path.

We've lost some test coverage here, but actually not too much if we consider that we are dropping GLSL input anyway.

* Fixup: test runner was mis-counting ignored tests

* Fixup: turn on dumping on test failure under Travis

* Fixup: enable extensions in Linux build of glslang

3 files changed, 71 insertions, 6 deletions

diff --git a/tests/render/cross-compile0.hlsl b/tests/render/cross-compile0.hlsl
index 861336b1c..889d3ec15 100644
--- a/tests/render/cross-compile0.hlsl
+++ b/tests/render/cross-compile0.hlsl
@@ -6,12 +6,11 @@
 // but the two will share a dependency on a file of
 // pure Spire code that provides the actual shading logic.
 
+#if defined(__HLSL__)
 
 // Pull in Spire code depdendency using extended syntax:
 __import cross_compile0;
 
-#if defined(__HLSL__)
-
 cbuffer Uniforms
 {
 	float4x4 modelViewProjection;
@@ -89,6 +88,24 @@ FragmentStageOutput fragmentMain(FragmentStageInput input)
 
 #version 420
 
+float saturate(float x)
+{
+    return clamp(x, float(0), float(1));	
+}
+
+vec3 transformColor(vec3 color)
+{
+	vec3 result;
+
+	result.x = sin(20.0 * (color.x + color.y));
+	result.y = saturate(cos(color.z * 30.0));
+	result.z = sin(color.x * color.y * color.z * 100.0);
+
+	result = 0.5 * (result + 1);
+
+	return result;
+}
+
 uniform Uniforms
 {
 	mat4x4 modelViewProjection;
diff --git a/tests/render/imported-parameters.hlsl b/tests/render/imported-parameters.hlsl
index 99216728e..faffeaf24 100644
--- a/tests/render/imported-parameters.hlsl
+++ b/tests/render/imported-parameters.hlsl
@@ -4,11 +4,11 @@
 // correctly handle cases where top-level shader
 // parameters are declared in an `import`ed file.
 
+#if defined(__HLSL__)
+
 // Pull in Spire code depdendency using extended syntax:
 __import imported_parameters;
 
-#if defined(__HLSL__)
-
 struct AssembledVertex
 {
 	float3	position;
@@ -81,6 +81,30 @@ FragmentStageOutput fragmentMain(FragmentStageInput input)
 
 #version 420
 
+layout(binding = 0)
+uniform Uniforms
+{
+	mat4x4 modelViewProjection;
+};
+
+float saturate(float x)
+{
+    return clamp(x, float(0), float(1));	
+}
+
+vec3 transformColor(vec3 color)
+{
+	vec3 result;
+
+	result.x = sin(20.0 * (color.x + color.y));
+	result.y = saturate(cos(color.z * 30.0));
+	result.z = sin(color.x * color.y * color.z * 100.0);
+
+	result = 0.5 * (result + 1);
+
+	return result;
+}
+
 #define ASSEMBLED_VERTEX(QUAL)		\
 	/* */
 
diff --git a/tests/render/unused-discard.hlsl b/tests/render/unused-discard.hlsl
index dad2f78e3..a47405f56 100644
--- a/tests/render/unused-discard.hlsl
+++ b/tests/render/unused-discard.hlsl
@@ -7,11 +7,11 @@
 // pure Spire code that provides the actual shading logic.
 
 
+#if defined(__HLSL__)
+
 // Pull in Spire code depdendency using extended syntax:
 __import unused_discard;
 
-#if defined(__HLSL__)
-
 cbuffer Uniforms
 {
 	float4x4 modelViewProjection;
@@ -91,6 +91,24 @@ FragmentStageOutput fragmentMain(FragmentStageInput input)
 
 #version 420
 
+float saturate(float x)
+{
+    return clamp(x, float(0), float(1));	
+}
+
+vec3 transformColor(vec3 color)
+{
+	vec3 result;
+
+	result.x = sin(20.0 * (color.x + color.y));
+	result.y = saturate(cos(color.z * 30.0));
+	result.z = sin(color.x * color.y * color.z * 100.0);
+
+	result = 0.5 * (result + 1);
+
+	return result;
+}
+
 uniform Uniforms
 {
 	mat4x4 modelViewProjection;
@@ -129,6 +147,12 @@ void main()
 
 #ifdef __GLSL_FRAGMENT__
 
+void doConditionalDiscard(vec3 color)
+{
+	if(color.x < 0.5)
+		discard;
+}
+
 V2F(in)
 
 layout(location = 0)