move cmake modules to a modules/ subdir

cmake/modules/CheckIeeeMath.cmake

@@ -0,0 +1,30 @@
+INCLUDE(CheckCXXSourceCompiles)
+
+MACRO (CHECK_IEEE_MATH _RESULT)
+
+SET(_CHECK_IEEE_MATH_SOURCE_CODE "
+
+#include<cmath>
+
+int main(int argc, char *argv[])
+{
+  double x = 1.0; double y = 1.0;
+  acosh(x); asinh(x); atanh(x);
+  expm1(x);
+  erf(x); erfc(x);
+  // finite(x);
+  isnan(x);
+  j0(x); j1(x);
+  lgamma(x);
+  logb(x); log1p(x);
+  rint(x);
+  // trunc(x);
+  y0(x); y1(x);
+  return 0;
+}
+
+")
+
+CHECK_CXX_SOURCE_COMPILES("${_CHECK_IEEE_MATH_SOURCE_CODE}" ${_RESULT})
+
+ENDMACRO (CHECK_IEEE_MATH)