MVKImage: Reject attempts to create compressed linear images.

This doesn't sit well with Metal, which will immediately abort the
program on the attempt.
diff --git a/MoltenVK/MoltenVK/GPUObjects/MVKImage.mm b/MoltenVK/MoltenVK/GPUObjects/MVKImage.mm
index 951e6f7..edd75f7 100644
--- a/MoltenVK/MoltenVK/GPUObjects/MVKImage.mm
+++ b/MoltenVK/MoltenVK/GPUObjects/MVKImage.mm
@@ -960,6 +960,10 @@
 		setConfigurationResult(reportError(VK_ERROR_FEATURE_NOT_PRESENT, "vkCreateImage() : If tiling is VK_IMAGE_TILING_LINEAR, format must not be a depth/stencil format."));
 		isLin = false;
 	}
+	if (getPixelFormats()->getFormatType(pCreateInfo->format) == kMVKFormatCompressed) {
+		setConfigurationResult(reportError(VK_ERROR_FEATURE_NOT_PRESENT, "vkCreateImage() : If tiling is VK_IMAGE_TILING_LINEAR, format must not be a compressed format."));
+		isLin = false;
+	}
 
 	if (pCreateInfo->mipLevels > 1) {
 		setConfigurationResult(reportError(VK_ERROR_FEATURE_NOT_PRESENT, "vkCreateImage() : If tiling is VK_IMAGE_TILING_LINEAR, mipLevels must be 1."));