Add a testcase for PR binutils/23460

Add a testcase to limit open files to 16 for AR with plugin.  Before

commit 103da91bc0
Author: Nick Clifton <nickc@redhat.com>
Date:   Wed Aug 1 14:34:41 2018 +0100

    Close resource leaks in the BFD library's plugin handler.

it failed with:

../binutils/ar: tmpdir/pr23460f.o: plugin needed to handle lto object

	PR binutils/23460
	* testsuite/ld-plugin/lto.exp: Run the PR binutils/23460 test.
	* testsuite/ld-plugin/pr23460a.c: New file.
	* testsuite/ld-plugin/pr23460b.c: Likewise.
	* testsuite/ld-plugin/pr23460c.c: Likewise.
	* testsuite/ld-plugin/pr23460d.c: Likewise.
	* testsuite/ld-plugin/pr23460e.c: Likewise.
	* testsuite/ld-plugin/pr23460f.c: Likewise.

ld/ChangeLog

@@ -1,3 +1,14 @@
+2018-08-02  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR binutils/23460
+	* testsuite/ld-plugin/lto.exp: Run the PR binutils/23460 test.
+	* testsuite/ld-plugin/pr23460a.c: New file.
+	* testsuite/ld-plugin/pr23460b.c: Likewise.
+	* testsuite/ld-plugin/pr23460c.c: Likewise.
+	* testsuite/ld-plugin/pr23460d.c: Likewise.
+	* testsuite/ld-plugin/pr23460e.c: Likewise.
+	* testsuite/ld-plugin/pr23460f.c: Likewise.
+
 2018-08-01  Roland McGrath  <mcgrathr@google.com>
 
 	* testsuite/ld-aarch64/ifunc-1-local.d: Adjust regexps to match

ld/testsuite/ld-plugin/lto.exp

@@ -556,6 +556,32 @@ if { [at_least_gcc_version 4 7] } {
     } {
         fail $testname
     }
+
+    run_cc_link_tests [list \
+	[list \
+	    "Build pr23460*.o" \
+	    "$plug_opt" \
+	    "-O2 -fPIC -flto $lto_no_fat" \
+	    {pr23460a.c pr23460b.c pr23460c.c \
+	     pr23460d.c pr23460e.c pr23460f.c} \
+	] \
+    ]
+    set exec_output [run_host_cmd "sh" \
+				  "-c \"ulimit -n 16; \
+				   $ar -rc $plug_opt \
+				   tmpdir/libpr23460.a \
+				   tmpdir/pr23460a.o \
+				   tmpdir/pr23460b.o \
+				   tmpdir/pr23460c.o \
+				   tmpdir/pr23460d.o \
+				   tmpdir/pr23460e.o \
+				   tmpdir/pr23460f.o\""]
+    set exec_output [prune_warnings $exec_output]
+    if [string match "" $exec_output] then {
+	pass "PR binutils/23460"
+    } else {
+	fail "PR binutils/23460"
+    }
 }
 
 # Run "ld -r" to generate inputs for complex LTO tests.

ld/testsuite/ld-plugin/pr23460a.c

@@ -0,0 +1,4 @@
+void
+x1 (void)
+{
+}

ld/testsuite/ld-plugin/pr23460b.c

@@ -0,0 +1,4 @@
+void
+x2 (void)
+{
+}

ld/testsuite/ld-plugin/pr23460c.c

@@ -0,0 +1,4 @@
+void
+x3 (void)
+{
+}

ld/testsuite/ld-plugin/pr23460d.c

@@ -0,0 +1,4 @@
+void
+x4 (void)
+{
+}

ld/testsuite/ld-plugin/pr23460e.c

@@ -0,0 +1,4 @@
+void
+x5 (void)
+{
+}

ld/testsuite/ld-plugin/pr23460f.c

@@ -0,0 +1,4 @@
+void
+x6 (void)
+{
+}