Revert "[flang][runtime] Enable I/O APIs in F18 runtime offload builds." (#87629)

Reverts #87543

The pre-merge Windows build is broken.

Author: joker-eph

flang/include/flang/Runtime/io-api.h

@@ -49,7 +49,6 @@ static void SetEnvironmentDefaults(const EnvironmentDefaultList *envDefaults) {
   }
 }
 
-RT_OFFLOAD_API_GROUP_BEGIN
 Fortran::common::optional<Convert> GetConvertFromString(
     const char *x, std::size_t n) {
   static const char *keywords[]{
@@ -69,7 +68,6 @@ Fortran::common::optional<Convert> GetConvertFromString(
     return Fortran::common::nullopt;
   }
 }
-RT_OFFLOAD_API_GROUP_END
 
 void ExecutionEnvironment::Configure(int ac, const char *av[],
     const char *env[], const EnvironmentDefaultList *envDefaults) {

flang/runtime/environment.cpp

@@ -31,7 +31,7 @@ RT_OFFLOAD_VAR_GROUP_END
 // External unformatted I/O data conversions
 enum class Convert { Unknown, Native, LittleEndian, BigEndian, Swap };
 
-RT_API_ATTRS Fortran::common::optional<Convert> GetConvertFromString(
+Fortran::common::optional<Convert> GetConvertFromString(
     const char *, std::size_t);
 
 struct ExecutionEnvironment {

flang/runtime/environment.h

@@ -52,11 +52,6 @@
 #define STD_STRCPY_UNSUPPORTED 1
 #endif
 
-#if !defined(STD_STRCMP_UNSUPPORTED) && \
-    (defined(__CUDACC__) || defined(__CUDA__)) && defined(__CUDA_ARCH__)
-#define STD_STRCMP_UNSUPPORTED 1
-#endif
-
 namespace Fortran::runtime {
 
 #if STD_FILL_N_UNSUPPORTED
@@ -181,19 +176,5 @@ static inline RT_API_ATTRS char *strcpy(char *dest, const char *src) {
 using std::strcpy;
 #endif // !STD_STRCPY_UNSUPPORTED
 
-#if STD_STRCMP_UNSUPPORTED
-// Provides alternative implementation for std::strcmp(), if
-// it is not supported.
-static inline RT_API_ATTRS int strcmp(const char *lhs, const char *rhs) {
-  while (*lhs != '\0' && *lhs == *rhs) {
-    ++lhs;
-    ++rhs;
-  }
-  return static_cast<unsigned char>(*lhs) - static_cast<unsigned char>(*rhs);
-}
-#else // !STD_STRCMP_UNSUPPORTED
-using std::strcmp;
-#endif // !STD_STRCMP_UNSUPPORTED
-
 } // namespace Fortran::runtime
 #endif // FORTRAN_RUNTIME_FREESTANDING_TOOLS_H_