Support all LLVM versions with same maximum major version

This should reduce the noise required to support newly released LLVM
versions, as we don't have to explicitly opt in to all minor and patch
releases. This assumes that all newer minor/patch versions are strict
improvements on previous versions.

The minimum version has been kept fully qualified as it is feasible that
we may require a minor/patch versions as a minimum.

cmake/ImportLLVM.cmake

@@ -76,19 +76,23 @@ include(DetectLLVMMSVCCRT)
   a supported version.
 #]=======================================================================]
 set(CA_LLVM_MINIMUM_VERSION 16.0.0)
-set(CA_LLVM_MAXIMUM_VERSION 17.0.1)
+set(CA_LLVM_MAXIMUM_VERSION 17)
 string(REPLACE ";" "', '" CA_LLVM_VERSIONS_PRETTY "${CA_LLVM_VERSIONS}")
 if("${LLVM_PACKAGE_VERSION}" VERSION_LESS "${CA_LLVM_MINIMUM_VERSION}")
   message(FATAL_ERROR
-    "LLVM version '${LLVM_PACKAGE_VERSION}' is not supported. oneAPI Construction Kit "
-    "supports released versions between: "
-    "'${CA_LLVM_MINIMUM_VERSION}' and '${CA_LLVM_MAXIMUM_VERSION}'.")
+    "LLVM version '${LLVM_PACKAGE_VERSION}' is not supported. oneAPI
+    Construction Kit " "supports released versions between: "
+    "'${CA_LLVM_MINIMUM_VERSION}' and '${CA_LLVM_MAXIMUM_VERSION}.x'.")
 else()
-  if("${LLVM_PACKAGE_VERSION}" VERSION_GREATER "${CA_LLVM_MAXIMUM_VERSION}")
+  # We notionally support all minor/patch versions of our maximum supported
+  # LLVM major version. Grab the *next* version after this, to warn users that
+  # they may be using a newer untested/unsupported version of LLVM.
+  MATH(EXPR MAX_LLVM_VER_PLUS_ONE "${CA_LLVM_MAXIMUM_VERSION}+1")
+  if("${LLVM_PACKAGE_VERSION}" VERSION_GREATER_EQUAL "${MAX_LLVM_VER_PLUS_ONE}")
     message(AUTHOR_WARNING
       "Build with LLVM version '${LLVM_PACKAGE_VERSION}' which is not "
       "supported. oneAPI Construction Kit supports released versions between: "
-      "'${CA_LLVM_MINIMUM_VERSION}' and '${CA_LLVM_MAXIMUM_VERSION}'.")
+      "'${CA_LLVM_MINIMUM_VERSION}' and '${CA_LLVM_MAXIMUM_VERSION}.x'.")
   endif()
 endif()
 message(STATUS "oneAPI Construction Kit using LLVM ${LLVM_PACKAGE_VERSION}")