Changeset [20797] breaks configure on FreeBSD

[Raymond Wagner <raymond@…>]

The configure script will not automatically search through /usr/local/include causing configure to fail to pick up Lame (and likely other dependencies). Normally, this is fixed just with a '--extra-cflags=-I/usr/local/include --extra-ldflags=-L/usr/local/lib', however the change to configure in [20797] now results in:

-D_ISOC99_SOURCE: not found
WARNING! An unknown C compiler flag in: "-I/usr/local/include". Option(s) will be ignored.

I'm looking through the diff to try to figure out what the problem is.

[Raymond Wagner <raymond@…>]

Configure runs fine if additional flags are added to the environment rather than through the configure line.

env CFLAGS=-I/usr/local/include LDFLAGS=-L/usr/local/lib ./configure  ....

[Dibblah]

At the point where check_ecflags is run, cc is unset. I am not sure of the reason for this, but this particular error appears to be indicative of a deeper issue.

[Janne Grunau]

(In [20888]) add C++ compiler sanity check. Fixes #6709

extra cflags and cxxflags can only checked after C and C++ compiler are set i.e. after the command line parse loop. So we add the flags without checking in the loop and run compiler sanity checks early. Adds a hint to check extra flags if the compiler checks fail.