Testsuite: Account for macOS 15 cpp file path changes

And add a procedure for getting the macOS version, which could be used
to look for specifically for the behavior of macOS 15 versus earlier
versions, but decided just to use a wildcard for the directory

testsuite/bsc.driver/cpp/cpp.exp

@@ -9,11 +9,12 @@ compile_fail_error Cpreprocess1.bsv P0210
 #multiple error messages, and it should not get confused about which
 #file we are in and what line we are on.
 compile_fail Cpreprocess_line.bsv -cpp
-# macOS preprocessor prepends './' to included file names
+# macOS preprocessor prepends './' to included file names for macOS 14 and earlier
+# and uses absolute path for macOS 15
 if { [which_os] == "Darwin" } {
     sed Cpreprocess_line.bsv.bsc-out \
 	Cpreprocess_line.bsv.bsc-out.filtered \
-	{} {-e {s/".\/more.bsv"/"more.bsv"/g}}
+	{} {-e {s/".*\/more.bsv"/"more.bsv"/g}}
     move Cpreprocess_line.bsv.bsc-out.filtered \
 	Cpreprocess_line.bsv.bsc-out
 }

testsuite/config/unix.exp

@@ -209,6 +209,18 @@ proc which_mach {} {
     return $env(MACHTYPE)
 }
 
+proc which_macos {} {
+    if { [catch "exec sw_vers -productVersion | cut -d '.' -f 1" version] } {
+	perror "failed to execute sw_vers to get macOS version: $version"
+	exit 1
+    }
+    if { $version == "" } {
+	perror "macOS version is empty"
+	exit 1
+    }
+    return $version
+}
+
 # return true if the given Bluetcl packahe is available
 proc bluetcl_package_available { pkg } {
     global bluetcl