Introduce __ARM_ACLE_VERSION macro. (#302)

main/acle.md

@@ -355,6 +355,7 @@ Armv8.4-A [[ARMARMv84]](#ARMARMv84). Support is added for the Dot Product intrin
 
 * Changed the definition of the `__ARM_ACLE` macro to reflect the current
   versioning scheme.
+* Added `__ARM_ACLE_VERSION` to express a given ACLE version.
 * Combined the SME `slice_base` and `slice_offset` arguments into a
   single `slice` argument.
 * Added the [Keyword attributes](#keyword-attributes) section.
@@ -1350,6 +1351,15 @@ version of this specification implemented. For instance, an implementation
 implementing version 2.1 of the ACLE specification defined `__ARM_ACLE`
 as `201`.
 
+`__ARM_ACLE_VERSION(year, quarter, patch)` is defined to express a given
+ACLE version. Returns with the version number in the same format as the
+`__ARM_ACLE` does. Checking the minimum required ACLE version could be
+written as:
+
+``` c
+#if __ARM_ACLE >= __ARM_ACLE_VERSION(2024, 1, 0)
+```
+
 ## Endianness
 
 `__ARM_BIG_ENDIAN` is defined as 1 if data is stored by default in