[libc][math] undef iscanonical before defining it using LLVM_LIBC_FUNCTION macro (llvm#110865)

It appears that llvm#110565 fails because the macro definition of
iscanonical is included somewhere. This PR ensures that the macro
expands correctly and also removes the static_cast because implicit
conversion from bool to int is defined in C++.

Author: Sh0g0-1758

libc/src/math/generic/iscanonical.cpp

@@ -13,9 +13,10 @@
 
 namespace LIBC_NAMESPACE_DECL {
 
+#undef iscanonical
 LLVM_LIBC_FUNCTION(int, iscanonical, (double x)) {
   double temp;
-  return static_cast<int>(fputil::canonicalize(temp, x) == 0);
+  return fputil::canonicalize(temp, x) == 0;
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/math/generic/iscanonicalf.cpp

@@ -15,7 +15,7 @@ namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, iscanonicalf, (float x)) {
   float temp;
-  return static_cast<int>(fputil::canonicalize(temp, x) == 0);
+  return fputil::canonicalize(temp, x) == 0;
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/math/generic/iscanonicalf128.cpp

@@ -15,7 +15,7 @@ namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, iscanonicalf128, (float128 x)) {
   float128 temp;
-  return static_cast<int>(fputil::canonicalize(temp, x) == 0);
+  return fputil::canonicalize(temp, x) == 0;
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/math/generic/iscanonicalf16.cpp

@@ -15,7 +15,7 @@ namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, iscanonicalf16, (float16 x)) {
   float16 temp;
-  return static_cast<int>(fputil::canonicalize(temp, x) == 0);
+  return fputil::canonicalize(temp, x) == 0;
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/math/generic/iscanonicall.cpp

@@ -15,7 +15,7 @@ namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, iscanonicall, (long double x)) {
   long double temp;
-  return static_cast<int>(fputil::canonicalize(temp, x) == 0);
+  return fputil::canonicalize(temp, x) == 0;
 }
 
 } // namespace LIBC_NAMESPACE_DECL