Fix test failure on systems with libstdc++ corresponding to gcc7.

This fixes #664.

As reported by @jirislaby the `test/Feature/LongDouble.cpp` test
fails to compile with Clang 3.4 due to new changes the libstdc++
headers. This ends up giving errors like

```
In file included from /home/abuild/rpmbuild/BUILD/klee-1.3.0+20170409/test/Feature/LongDouble.cpp:12:
In file included from /usr/bin/../lib64/gcc/x86_64-suse-linux/7/../../../../include/c++/7/cstdlib:77:
/usr/bin/../lib64/gcc/x86_64-suse-linux/7/../../../../include/c++/7/bits/std_abs.h:101:3: error: unknown type name '__float128'
  __float128
  ^
/usr/bin/../lib64/gcc/x86_64-suse-linux/7/../../../../include/c++/7/bits/std_abs.h:102:7: error: unknown type name '__float128'
  abs(__float128 __x)
      ^
2 errors generated.
```

Clang 4.0 seems fine with this source file so the problem has already
been addressed upstream so we don't need to file a bug. We just need
to move to a newer LLVM version to fix this properly!

To work around this the test has been made into a C program rather than
a C++ program to avoid including the C++ headers. The program wasn't
using any important C++ features anyway so this seems like a sensible change.

1 files changed, 0 insertions, 64 deletions

diff --git a/test/Feature/LongDouble.cpp b/test/Feature/LongDouble.cpp
deleted file mode 100644
index 08924293..00000000
--- a/test/Feature/LongDouble.cpp
+++ /dev/null
@@ -1,64 +0,0 @@
-// RUN: %llvmgxx -I../../../include -g -fno-exceptions -emit-llvm -O0 -c -o %t.bc %s
-// RUN: rm -rf %t.klee-out
-// RUN: %klee --output-dir=%t.klee-out --libc=klee --no-output --exit-on-error %t.bc > %t.log
-// RUN: grep -q powl\(-11\\.0,0\)=1\\.0\\+ %t.log
-// RUN: grep -q powl\(-11\\.0,1\)=-11\\.0\\+ %t.log
-// RUN: grep -q powl\(-11\\.0,2\)=121\\.0\\+ %t.log
-// RUN: grep -q 1/0=inf %t.log
-// RUN: grep -q 1/-1=-1\\.0\\+ %t.log
-// RUN: grep -q 1/-2=-0\\.50\\+ %t.log
-
-#include <cstdio>
-#include <cstdlib>
-#include <cmath>
-#include <cassert>
-
-#include "klee/klee.h"
-
-unsigned klee_urange(unsigned start, unsigned end) {
-  unsigned x;
-  klee_make_symbolic(&x, sizeof x, "x");
-  if (x-start>=end-start) klee_silent_exit(0);
-  return x;
-}
-
-int main(int argc, char ** argv)
-{
-
-  int a = klee_urange(0,3);
-  int b;
-
-  // fork states
-  switch(a) {
-  case 0:
-    b = -0;
-    break;
-  case 1:
-    b = -1;
-    break;
-  case 2:
-    b = -2;
-    break;
-  default:
-    assert(false && "Impossible switch target");
-  }
-
-  // test 80-bit external dispatch
-  long double d = powl((long double)-11.0, (long double)a);
-  // FIXME: Use CHECK-DAG: with FileCheck tool
-  // CHECK-DAG: powl(-11.0,0)=1.0
-  // CHECK-DAG: powl(-11.0,1)=-11.0
-  // CHECK-DAG: powl(-11.0,2)=121.0
-  printf("powl(-11.0,%d)=%Lf\n", a, d);
-
-  // test 80-bit fdiv
-  long double e = (long double) 1 / (long double) b;
-  // CHECK-DAG: 1/0=inf
-  // CHECK-DAG: 1/1-1=-1.0
-  // CHECK-DAG: 1/-2=-0.50
-  printf("1/%d=%Lf\n", b, e);
-
-  return 0;
-}
-
-