libm.so.2 failure in many places

[Christoph Kukulies]

In 4.8 (the fallback release for me now after 5.0 and 5.0-current turns out
to be unreliable and slow) compilation of ports and running existing
binaries fails in many places due to :

configure:29021: checking for png_write_image in -lpng
configure:29040: cc -o conftest -O -pipe  -I/usr/local/include  -DDOCUMENT_LOCAT
ION="/usr/local/www/data" -DDEFAULT_PATH="/bin:/usr/bin:/usr/local/bin" -DHARD_S
ERVER_LIMIT=512 -DUSE_EXPAT
      -L/usr/lib -lz -L/usr/local/lib
      -R/usr/local/lib -L/usr/local/lib conftest.c -lpng  -ljpeg -lz -lcrypt  -l
crypt 1>&5
/usr/lib/libm.so.2: undefined reference to `__fpclassifyd'
/usr/lib/libm.so.2: undefined reference to `__fpclassifyf'
configure: failed program was:
#line 29029 "configure"
#include "confdefs.h"
/* Override any gcc2 internal prototype to avoid an error.  */
/* We use char because int might match the return type of a gcc2
    builtin and then its argument prototype would still apply.  */
char png_write_image();

int main() {
png_write_image()
; return 0; }

What is the fix for this? 

--
Chris Christoph P. U. Kukulies kukulies at rwth-aachen.de