on Solaris even though it is available, and declare it ourselves in
that case. (Bug #7156)


configure.in:
  Add test for madvise() being declared when C++ compiler is used.
include/my_global.h:
  Handle madvise() being available but not declared in C++
isam/extra.c:
  Fix typo in define test
myisam/mi_extra.c:
  Fix typo in define test
sql/examples/ha_tina.cc:
  Test that we have madvise() before trying to call it.