Merge branch '3.2-maint'

Merge branch '3.2-maint'

* 3.2-maint:
  Include strings.h for strcasecmp
  Remove unnecessary extra_cppflags, extra_ldflags and all_ldflags variables
  Improve signal handling
  Wait for compiler subprocess to exit before exiting from a signal
  Make conversion-to-bool explicit to avoid warnings on legacy systems
  Fix regression in recent change related to zlib in nonstandard location

Conflicts:
	NEWS.txt