BUILD: fix "make install" to support spaces in the install dirs

Makefile is unable to install into directories containing spaces.
(cherry picked from commit 3785311e64792787de78370fa126fd806734f7fe)
BUG/MEDIUM: ssl: fix bad ssl context init can cause segfault in case of OOM.

Some SSL context's init functions errors were not handled and
can cause a segfault due to an incomplete SSL context
initialization.

This fix must be backported to 1.5.
(cherry picked from commit 5547615cdac377797ae351a2e024376dbf6d6963)
BUG/MEDIUM: ssl: force a full GC in case of memory shortage

When memory becomes scarce and openssl refuses to allocate a new SSL
session, it is worth freeing the pools and trying again instead of
rejecting all incoming SSL connection. This can happen when some
memory usage limits have been assigned to the haproxy process using
-m or with ulimit -m/-v.

This is mostly an enhancement of previous fix and is worth backporting
to 1.5.
(cherry picked from commit fba03cdc5ac6e3ca318b34915596cbc0a0dacc55)