test 518 is all about testing libcurl functionality

when more than FD_SETSIZE file descriptors are open.
This means that if for any reason we are not able to
open more than FD_SETSIZE file descriptors then test
518 should not be run.

test 537 is all about testing libcurl functionality
when the system has nearly exhausted the number of
free file descriptors. Test 537 will try to run with
very few free file descriptors.

tests/data/Makefile.am

@@ -36,4 +36,4 @@ EXTRA_DIST = test1 test108 test117 test127 test20 test27 test34 test46	   \
  test265 test266 test267 test268 test269 test270 test271 test272 test273   \
  test274 test275 test524 test525 test276 test277 test526 test527 test528   \
  test530 DISABLED test278 test279 test531 test280 test529 test532 test533  \
- test534 test535 test281
+ test534 test535 test281 test537

tests/data/test537

@@ -0,0 +1,55 @@
+#
+# Server-side
+<reply>
+<data>
+HTTP/1.1 200 OK
+Date: Thu, 09 Nov 2010 14:49:00 GMT
+Server: test-server/fake
+Last-Modified: Tue, 13 Jun 2000 12:10:00 GMT
+ETag: "21025-dc7-39462498"
+Accept-Ranges: bytes
+Content-Length: 6
+Connection: close
+Content-Type: text/html
+Funny-head: yesyes
+
+<foo>
+</data>
+</reply>
+
+# Client-side
+<client>
+<server>
+http
+</server>
+<features>
+getrlimit
+</features>
+# tool is what to use instead of 'curl'
+<tool>
+lib537
+</tool>
+# precheck is a command line to run before the test, to see if we can execute
+# the test or not
+<precheck>
+./libtest/lib537 check
+</precheck>
+
+ <name>
+HTTP GET with a HUGE number of file descriptors open
+ </name>
+ <command>
+http://%HOSTIP:%HTTPPORT/537
+</command>
+</client>
+
+#
+# Verify data after the test has been "shot"
+<verify>
+<protocol>
+GET /537 HTTP/1.1
+Host: 127.0.0.1:%HTTPPORT
+Accept: */*
+
+</protocol>
+</verify>