Core/Executor: long double on i686 must be aligned to 4 bytes

According to i686 System V ABI 2.1.1, long double must be aligned to 4 bytes.
Thus, its size with padding is 12 bytes.  Prior to this change only 10 bytes
were used.

This commit fixes the following out of bound pointer access.
```
$ clang -m32 -O0 -Xclang -disable-O0-optnone -g -emit-llvm -c test/Feature/VarArgAlignment.c -o varalign.bc
$ klee varalign.bc
KLEE: output directory is "/home/lukas/klee/klee-out-19"
KLEE: Using Z3 solver backend
KLEE: WARNING: undefined reference to function: printf
KLEE: WARNING ONCE: calling external: printf(44120064, 1, 2, 3) at test/Feature/VarArgAlignment.c:23 17
i1, i2, i3: 1, 2, 3
l1: 4
i4: 5
ld1: 6.000000
KLEE: ERROR: test/Feature/VarArgAlignment.c:35: memory error: out of bound pointer
KLEE: NOTE: now ignoring this error at this location

KLEE: done: total instructions = 499
KLEE: done: completed paths = 1
KLEE: done: generated tests = 1
```

0 files changed, 0 insertions, 0 deletions