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, 13 insertions, 16 deletions

diff --git a/test/Feature/LongDouble.cpp b/test/Feature/LongDouble.c
index 08924293..ad4c1a79 100644
--- a/test/Feature/LongDouble.cpp
+++ b/test/Feature/LongDouble.c
@@ -1,6 +1,7 @@
-// RUN: %llvmgxx -I../../../include -g -fno-exceptions -emit-llvm -O0 -c -o %t.bc %s
+// RUN: %llvmgcc  -g -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
+// FIXME: When we remove LLVM 2.9 support just use FileCheck and remove these `grep`s.
 // 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
@@ -8,28 +9,26 @@
 // 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"
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.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);
+  if (x - start >= end - start)
+    klee_silent_exit(0);
   return x;
 }
 
-int main(int argc, char ** argv)
-{
-
-  int a = klee_urange(0,3);
+int main(int argc, char **argv) {
+  int a = klee_urange(0, 3);
   int b;
 
   // fork states
-  switch(a) {
+  switch (a) {
   case 0:
     b = -0;
     break;
@@ -40,7 +39,7 @@ int main(int argc, char ** argv)
     b = -2;
     break;
   default:
-    assert(false && "Impossible switch target");
+    assert(0 && "Impossible switch target");
   }
 
   // test 80-bit external dispatch
@@ -52,7 +51,7 @@ int main(int argc, char ** argv)
   printf("powl(-11.0,%d)=%Lf\n", a, d);
 
   // test 80-bit fdiv
-  long double e = (long double) 1 / (long double) b;
+  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
@@ -60,5 +59,3 @@ int main(int argc, char ** argv)
 
   return 0;
 }
-
-