Remove fragile xallocx() test case.
Remove fragile xallocx() test case.

In addition to depending on map coalescing, the test depended on
munmap() being disabled so that chunk recycling would always succeed.

jemalloc/jemalloc-cmake,AndroidExternal/jemalloc,flyfeifan/jemalloc,leebaok/jemalloc-4.2.1-readcode,AndroidExternal/jemalloc,wqfish/jemalloc,leebaok/jemalloc-4.2.1-readcode,VRToxin/android_external_jemalloc,leebaok/jemalloc-4.2.1-readcode,wqfish/jemalloc,AndroidExternal/jemalloc,glandium/jemalloc,jemalloc/jemalloc-cmake,cpeterso/jemalloc,8l/jemalloc,awreece/jemalloc,wqfish/jemalloc,VRToxin/android_external_jemalloc,8l/jemalloc,VRToxin/android_external_jemalloc,CMRemix/android_external_jemalloc,jemalloc/jemalloc-cmake,cpeterso/jemalloc,wqfish/jemalloc,8l/jemalloc,glandium/jemalloc,flyfeifan/jemalloc,awreece/jemalloc,flyfeifan/jemalloc,AndroidExternal/jemalloc,jemalloc/jemalloc-cmake,flyfeifan/jemalloc,CMRemix/android_external_jemalloc,8l/jemalloc,CMRemix/android_external_jemalloc,wqfish/jemalloc,VRToxin/android_external_jemalloc,awreece/jemalloc,awreece/jemalloc,glandium/jemalloc,glandium/jemalloc,CMRemix/android_external_jemalloc,leebaok/jemalloc-4.2.1-readcode,cpeterso/jemalloc,cpeterso/jemalloc