[libc] Fix scanf dependencies on the GPU build

Summary:
The GPU build doesn't have `file` as a struct but does use these
targets. We need to add an escape for this.

Author: jhuber6

libc/src/stdio/scanf_core/CMakeLists.txt

@@ -54,7 +54,8 @@ add_header_library(
     libc.src.__support.CPP.string_view
 )
 
-if(NOT(TARGET libc.src.__support.File.file) AND LLVM_LIBC_FULL_BUILD)
+if(NOT(TARGET libc.src.__support.File.file) AND LLVM_LIBC_FULL_BUILD AND
+  (NOT LIBC_TARGET_OS_IS_GPU))
   # Not all platforms have a file implementation. If file is unvailable, and a
   # full build is requested, then we must skip all file based scanf sections.
   return()

libc/test/src/stdio/scanf_core/CMakeLists.txt

@@ -18,7 +18,8 @@ add_libc_unittest(
     libc.src.__support.arg_list
 )
 
-if(NOT(TARGET libc.src.__support.File.file) AND LLVM_LIBC_FULL_BUILD)
+if(NOT(TARGET libc.src.__support.File.file) AND LLVM_LIBC_FULL_BUILD AND
+  (NOT LIBC_TARGET_OS_IS_GPU))
   # Not all platforms have a file implementation. If file is unvailable, and a
   # full build is requested, then we must skip all file based scanf sections.
   return()