Patch 1.49.3 for geodesic package.

[cffk]

Set flags for Intel compiler to prevent incorrect optimization of
arithmetic expressions #826. Guard against nans in sincosdx #843.
Issue #831 is not addressed here (need more information...).

@kbevers and @rouault I flagged some of the changes made to
satisfy cppcheck, e.g.,

    if ((outmask & GEOD_LATITUDE) && plat2) /* plat2 check redundant */
      *plat2 = lat2;

The outmask test makes the plat2 test unnecessary. So, if possible, I'd
like to back out of this change and revert to

    if (outmask & GEOD_LATITUDE) 

Sorry not to have caught this earlier.

[cffk]

The setting of the flags for the Intel compiler has been tested on Linux only (cmake + autoconf). I've specified the right flag for the Intel compiler on Windows (with cmake), but I haven't tested this.

[rouault]

The outmask test makes the plat2 test unnecessary.

This is actually not for cppcheck but for clang static analyzer, for which I don't know how to put suppressions as annotations in the code. This was so immediately obvious to me that the test is unnecessary. CSA is probably confused by the line "outmask &= l->caps & OUT_ALL;" which modifies the flags, but as and masking can only remove a bit, indeed the current code is correct, but it needs a (too) clever brain to realize it. I'd vote to let the additional check. If not, some exception should be added in the last line of travis/csa/install.sh

[cffk]

@rouault OK, I'll let it be. Maybe I'll change the comment to put the blame on CSA. (You'll see that I did the same with the initial assignments. Perhaps you can check that I blamed the right party!)

[cffk]

I can't easily debug the configuration failures on the CI machines. autogen.sh and configure work OK for me (Intel and gcc). I suspect something needs to be done to bring AX_CHECK_COMPILE_FLAG into scope. Worst comes to worst, I remove the changes to configure.ac and Intel is only supported via cmake.

[QuLogic]

You need to add the file defining the AX_CHECK_COMPILE_FLAG macro into the m4 directory (the autoconf archive is all copylibs).

[cffk]

@QuLogic Thanks that did it.
@mwtoews Perhaps you could verify that I've got the Intel flags right on as many platforms as possible (+ configure + cmake). Thanks.

[kbevers]

cherry-picked into 5.0 branch