Fix Asan-i386-calls-Test AddressSanitizer.ShadowGapTest on FreeBSD

0x22000000 happens to be on the left of a heap allocation and the error
message is different (heap-buffer-overflow).
FreeBSD NetBSD have larger SHADOW_OFFSET (0x40000000) but let's try not
using #ifdef here.

llvm-svn: 338208