Fix ld tests with sysroot=/ and --enable-targets=all and test --print-sysroot

	* ld-scripts/sysroot-prefix.exp: Log $ld_sysroot.  Handle sysroot
	== "/" as a separate sysroot-configuration with separable
	test-types.
	(sysroot_prefix_tests): Include all existing sysroot tests in
	sysroot == "/" tests except exclude those where a --sysroot option
	is not specified.
	* lib/ld-lib.exp (check_sysroot_available): Rewrite to use
	--print-sysroot instead of relying on error code from using
	--sysroot=...  Also, set $ld_sysroot.

The reason we exclude not just the failing "full-path =-prefixed
without" but also the passing "plain =-prefixed without but -Lpath"
for sysroot == "/" is that for the latter to succeed, we have to make
assumptions about the system not having a /sysroot directory or
assumptions about its contents etc.

When passing --enable-targets=all --enable-64-bit-bfd (the
latter not required for a "64-bit-host" of course) the ld --help
output got too much to handle for poor tcl (or maybe dejagnu is
to blame) and remote_exec exited with an error, so the
configuration being tested was mishandled as being a
sysroot-less configuration.  Using --version instead of --help
would work too, but the new --print-sysroot option calls for
nominal coverage, so why not use that instead.

1 files changed, 6 insertions, 8 deletions

diff --git a/ld/testsuite/lib/ld-lib.exp b/ld/testsuite/lib/ld-lib.exp
index ffdf805..7d2df22 100644
--- a/ld/testsuite/lib/ld-lib.exp
+++ b/ld/testsuite/lib/ld-lib.exp
@@ -1669,16 +1669,14 @@ proc check_plugin_api_available { } {
     return $plugin_api_available_saved
 }
 
-# Returns true if the target ld supports sysroot.
+# Sets ld_sysroot to the current sysroot (empty if not supported) and
+# returns true if the target ld supports sysroot.
 proc check_sysroot_available { } {
-    global ld_sysroot_available_saved
-    global ld
+    global ld_sysroot_available_saved ld ld_sysroot
     if {![info exists ld_sysroot_available_saved]} {
-	# Check if ld supports --sysroot *other* than empty
-	# (non-sysroot linkers don't emit errors for --sysroot="").
-	# The help-text by itself is no indication as it always lists --sysroot.
-	set status [remote_exec host $ld "--sysroot=ldxyzzy --help >/dev/null"]
-	if { [lindex $status 0] != 0 } {
+	# Check if ld supports --sysroot *other* than empty.
+	set ld_sysroot [string trimright [lindex [remote_exec host $ld "--print-sysroot"] 1]]
+	if { $ld_sysroot == "" } {
 	    set ld_sysroot_available_saved 0
 	} else {
 	    set ld_sysroot_available_saved 1