ab: don't call malloc_init for OpenSSL 1.1.0

Patch by rjung.

The 1.1.0 compatibility macro for OpenSSL_malloc_init() causes problems
when mixed with procedure linkage stubs with some toolchains (e.g. GCC).
OpenSSL's malloc implementation doesn't recognize that the PLT stub
points back to it, which leads to infinite recursion.

Since the 1.1.0 documentation states that calling this function
explicitly is no longer necessary except "in certain shared-library
situations"(?), get rid of it.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1795830 13f79535-47bb-0310-9956-ffa450edef68