The port must respect CFLAGS.
      What we mean by this is that the port must not set
      the value of this variable absolutely, overriding the existing
      value.  Instead, it may append whatever values it needs to the
      existing value.  This is so that build options that affect all
      ports can be set globally.
If it does not, please add
      NO_PACKAGE=ignores cflags to the
      Makefile.
Here is an example of a Makefile
      respecting CFLAGS.  Note the
      +=:
CFLAGS+= -Wall -Werror
Here is an example which does not respect
      CFLAGS:
CFLAGS= -Wall -Werror
CFLAGS is defined on
      FreeBSD systems in /etc/make.conf.  The first
      example appends additional flags to
      CFLAGS, preserving any system-wide
      definitions.  The second example clobbers anything previously
      defined.
Remove optimization flags from the third party
      Makefiles.  The system
      CFLAGS contains system-wide optimization
      flags.  An example from an unmodified
      Makefile:
CFLAGS= -O3 -funroll-loops -DHAVE_SOUND
Using system optimization flags, the
      Makefile would look similar to this
      example:
CFLAGS+= -DHAVE_SOUND
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