* Squash round() commits

- Add check in roundx() functions for infinite or NaN cases
  - Add block to avoid style warnings
  - Define long double constants and macros for infinity and nan
  - Correct return syntax to match NuttX style
  - Make c89 compliant
  - Fix definitions of INFINITY_L/NAN_L

* include/nuttx/lib/math.h - match standard naming conventions
  - Rename isinf_l to isinfl
  - Rename isinf_f to isinff
  - Add finite()
  - Add finitel()
  - Add finitef()
  - Define isnanl and isnanf
  - Define isfinite() so that it uses the appropriate macro

* libs/libc/math/lib_asinf.c
  libs/libc/math/lib_asinl.c
  libs/libc/math/lib_roundf.c
  libs/libc/math/lib_roundl.c
  libs/libc/math/lib_sqrtf.c
  libs/libc/math/lib_sqrtl.c
  - Use renamed macros
  - Use correct NAN_x or INFINIT_x macro on returns

libs/libc/math/lib_asinf.c

@@ -70,7 +70,7 @@ float asinf(float x)
 
   /* Verify that the input value is in the domain of the function */
 
-  if (x < -1.0F || x > 1.0F || isnan(x))
+  if (x < -1.0F || x > 1.0F || isnanf(x))
     {
       return NAN_F;
     }

libs/libc/math/lib_asinl.c

@@ -70,9 +70,9 @@ long double asinl(long double x)
 
   /* Verify that the input value is in the domain of the function */
 
-  if (x < -1.0 || x > 1.0 || isnan(x))
+  if (x < -1.0 || x > 1.0 || isnanl(x))
     {
-      return NAN;
+      return NAN_L;
     }
 
   /* if x is > sqrt(2), use identity for faster convergence */

libs/libc/math/lib_logf.c

@@ -102,12 +102,12 @@ float logf(float x)
 
   if (y == FLT_MAX_EXP_X)
     {
-      return INFINITY;
+      return INFINITY_F;
     }
 
   if (y == -FLT_MAX_EXP_X)
     {
-      return INFINITY;
+      return INFINITY_F;
     }
 
   return y;

libs/libc/math/lib_logl.c

@@ -78,12 +78,12 @@ long double logl(long double x)
 
   if (y == LDBL_MAX_EXP_X)
     {
-      return INFINITY;
+      return INFINITY_L;
     }
 
   if (y == -LDBL_MAX_EXP_X)
     {
-      return INFINITY;
+      return INFINITY_L;
     }
 
   return y;

libs/libc/math/lib_round.c

@@ -34,7 +34,14 @@
 #ifdef CONFIG_HAVE_DOUBLE
 double round(double x)
 {
-  double f = modf(x, &x);
+  double f;
+
+  if (isinf(x) || isnan(x))
+    {
+      return x;
+    }
+
+  f = modf(x, &x);
   if (x <= 0.0 && f <= -0.5)
     {
       x -= 1.0;

libs/libc/math/lib_roundf.c

@@ -33,7 +33,14 @@
 
 float roundf(float x)
 {
-  float f = modff(x, &x);
+  float f;
+
+  if (isinff(x) || isnanf(x))
+    {
+      return x;
+    }
+
+  f = modff(x, &x);
   if (x <= 0.0f && f <= -0.5f)
     {
       x -= 1.0f;

libs/libc/math/lib_roundl.c

@@ -34,7 +34,14 @@
 #ifdef CONFIG_HAVE_LONG_DOUBLE
 long double roundl(long double x)
 {
-  long double f = modfl(x, &x);
+  long double f;
+
+  if (isinfl(x) || isnanl(x))
+    {
+      return x;
+    }
+
+  f = modfl(x, &x);
   if (x <= 0.0 && f <= -0.5)
     {
       x -= 1.0;

libs/libc/math/lib_sqrtf.c

@@ -54,12 +54,12 @@ float sqrtf(float x)
       return NAN_F;
     }
 
-  if (isnan(x))
+  if (isnanf(x))
     {
       return NAN_F;
     }
 
-  if (isinf_f(x))
+  if (isinff(x))
     {
       return INFINITY_F;
     }

libs/libc/math/lib_sqrtl.c

@@ -52,17 +52,17 @@ long double sqrtl(long double x)
   if (x < 0.0)
     {
       set_errno(EDOM);
-      return NAN;
+      return NAN_L;
     }
 
-  if (isnan(x))
+  if (isnanl(x))
     {
-      return NAN;
+      return NAN_L;
     }
 
-  if (isinf(x))
+  if (isinfl(x))
     {
-      return INFINITY;
+      return INFINITY_L;
     }
 
   if (x == 0.0)