libCom/posix: Define finite() for uClibc

The finite() function is provided in glibc but not in uClibc.
C99 requires isfinite() to be a macro, so we can test for it
and define our own finite() macro in osi/os/posix/epicsMath.h

src/libCom/osi/os/posix/epicsMath.h

@@ -17,6 +17,11 @@
 extern "C" {
 #endif
 
+#ifdef isfinite
+#  undef finite
+#  define finite(x) isfinite(x)
+#endif
+
 epicsShareExtern float epicsNAN;
 epicsShareExtern float epicsINF;