include/cxx/cmath: Use toolchain <cmath> with toolchain libm.

When CONFIG_LIBM_TOOLCHAIN is enabled, include_next the toolchain\n<c\+\+>/cmath wrapper instead of importing symbols from the NuttX\ncmath shim. This avoids include-order recursion and lets libstdc\+\+\nresolve std::abs/std::acos/... against the matching toolchain C\nmath.h declarations.\n\nKeep the existing NuttX cmath namespace path unchanged for non-\ntoolchain libm configurations.

Signed-off-by: aviralgarg05 <gargaviral99@gmail.com>

include/cxx/cmath

@@ -30,7 +30,16 @@
 #include <nuttx/config.h>
 #include <nuttx/compiler.h>
 
-#include <math.h>
+#if defined(CONFIG_LIBM_TOOLCHAIN)
+/* In toolchain libm mode, use toolchain <cmath> so it can include_next the
+ * matching C math.h header and populate std::* consistently.
+ */
+
+#  include_next <cmath>
+
+#else
+
+#  include <math.h>
 
 #undef signbit
 #undef fpclassify
@@ -222,4 +231,6 @@ namespace std
 
 }
 
+#endif
+
 #endif // __INCLUDE_CXX_CMATH