With CGAL now being header-only and boost-1.77.0 dropping thread-mt (not
actually linking with it), these link attempts just cause unnecessary issues.

https://bugs.gentoo.org/790779
https://bugs.gentoo.org/808727
--- a/configure.ac
+++ b/configure.ac
@@ -227,5 +227,4 @@
       has_CGAL="yes  (found CGAL > v3)"
       AC_CHECK_LIB(gmp,__gmpq_init,,AC_MSG_ERROR([gmp library not found. Please install it.]))
-      AC_CHECK_LIB(boost_thread-mt,main,,AC_MSG_ERROR([boost_thread-mt library not found. Please install it.]))
     else
       AC_DEFINE([CGAL_VERSION3], [1], [CGAL_VERSION3 compatibility])
@@ -233,5 +232,5 @@
     fi   
     CGAL_CFLAGS=-frounding-math
-    CGAL_LIBS=-lCGAL
+    CGAL_LIBS=
     AC_DEFINE([WINDDATA3D], [1], [Import code for wind data, needs CGAL, 0 to disable])
 else