Fix for yaSSL link failures with Forte Developer 7, MIPSpro Compilers, Compaq C++.
These compilers have problem with implicit template instantiation in archives
(libyassl.a, libtaocrypt.a). Instantiate templates explicitly.

Fix for yaSSL link failure on powermacg5 (gcc 3.3). When -O3 is specified gcc inlines
__cxa_pure_virtual. This is wrong behavior, __cxa_pure_virtual must never be inlined.


configure.in:
  Better CXX_VERSION guessing.
  EXPLICIT_TEMPLATE_INSTANTIATION macro indicates whether to instantiate templates explicitly.
  Instantiate templates explicitly on MIPSpro, Compaq, Forte.
extra/yassl/src/crypto_wrapper.cpp:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
extra/yassl/src/template_instnt.cpp:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
  More portable templates instantiation.
extra/yassl/src/yassl_int.cpp:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
  More portable templates instantiation.
extra/yassl/taocrypt/include/runtime.hpp:
  Fix for link failure on powermacg5 (gcc 3.3). __cxa_pure_virtual must never be inlined.
extra/yassl/taocrypt/src/algebra.cpp:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
extra/yassl/taocrypt/src/integer.cpp:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
extra/yassl/taocrypt/src/template_instnt.cpp:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/field.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/item.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/item_buff.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/mysqld.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/opt_range.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/set_var.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/slave.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/sql_acl.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/sql_class.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/sql_insert.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/sql_map.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/sql_select.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/sql_show.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.
sql/table.cc:
  Replace __GNUC__ by EXPLICIT_TEMPLATE_INSTANTIATION.