Similar to the handling of darwin target triples, strip the version
numbers off of freebsd target triples, when generating the name of the
ABI list file for check-cxx-abilist target.

Also remove unnecessary parentheses in the regex for darwin, and
slightly reword the comment.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@342805 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/abi/CMakeLists.txt b/lib/abi/CMakeLists.txt
index e42e961..e65df03 100644
--- a/lib/abi/CMakeLists.txt
+++ b/lib/abi/CMakeLists.txt
@@ -1,9 +1,12 @@
 
 if (DEFINED TARGET_TRIPLE)
-    # Ignore the major, minor, and patchlevel versions of the darwin
-    # target.
-    string(REGEX REPLACE "darwin([0-9]+)\\.([0-9]+)\\.([0-9]+)" "darwin"
-      GENERIC_TARGET_TRIPLE "${TARGET_TRIPLE}")
+    # Ignore the major, minor, and patchlevel versions of darwin targets.
+    string(REGEX REPLACE "darwin[0-9]+\\.[0-9]+\\.[0-9]+" "darwin"
+           GENERIC_TARGET_TRIPLE "${TARGET_TRIPLE}")
+
+    # Ignore the major and minor versions of freebsd targets.
+    string(REGEX REPLACE "freebsd[0-9]+\\.[0-9]+" "freebsd"
+           GENERIC_TARGET_TRIPLE "${TARGET_TRIPLE}")
 endif()
 
 # Detect if we are building in the same configuration used to generate