[libc][errno] remove mips+sparc specific errnos (#92798)

These are untested and unsupported platforms. The pattern used makes sense for
platform specific error numbers, but these are platforms we do not support.
Excise this code.

Link: #91150

Author: nickdesaulniers

libc/include/llvm-libc-macros/linux/CMakeLists.txt

@@ -1,13 +1,7 @@
-add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/mips)
-add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/sparc)
-
 add_header(
   error_number_macros
   HDR
     error-number-macros.h
-  DEPENDS
-    .mips.error_number_macros
-    .sparc.error_number_macros
 )
 
 add_header(

libc/include/llvm-libc-macros/linux/error-number-macros.h

@@ -1,13 +1,6 @@
 #ifndef LLVM_LIBC_MACROS_LINUX_ERROR_NUMBER_MACROS_H
 #define LLVM_LIBC_MACROS_LINUX_ERROR_NUMBER_MACROS_H
 
-#if defined(__mips__)
-#include "mips/error-number-macros.h"
-
-#elif defined(__sparc__)
-#include "sparc/error-number-macros.h"
-
-#else
 #ifndef ECANCELED
 #define ECANCELED 125
 #endif // ECANCELED
@@ -27,6 +20,5 @@
 #ifndef EHWPOISON
 #define EHWPOISON 133
 #endif // EHWPOISON
-#endif
 
 #endif // LLVM_LIBC_MACROS_LINUX_ERROR_NUMBER_MACROS_H