Attempt to fix linker error

From:
https://github.com/llvm/llvm-project/actions/runs/12518682283/job/34921546556?pr=121215
Error was:
```
/usr/bin/ld: libc/src/stdio/scanf_core/CMakeFiles/libc.src.stdio.scanf_core.reader.dir/./reader.cpp.o: in function `__llvm_libc_20_0_0_git::scanf_core::Reader::getc()':
reader.cpp:(.text._ZN22__llvm_libc_20_0_0_git10scanf_core6Reader4getcEv+0x38): undefined reference to `__llvm_libc_20_0_0_git::File::read_unlocked(void*, unsigned long)'
/usr/bin/ld: libc/src/stdio/scanf_core/CMakeFiles/libc.src.stdio.scanf_core.reader.dir/./reader.cpp.o: in function `__llvm_libc_20_0_0_git::scanf_core::Reader::ungetc(char)':
reader.cpp:(.text._ZN22__llvm_libc_20_0_0_git10scanf_core6Reader6ungetcEc+0x2c): undefined reference to `__llvm_libc_20_0_0_git::File::ungetc_unlocked(int)'
/usr/bin/ld: libc/test/src/stdio/libc.test.src.stdio.sscanf_test.__unit__.__build__: hidden symbol `_ZN22__llvm_libc_20_0_0_git4File13read_unlockedEPvm' isn't defined
/usr/bin/ld: final link failed: bad value
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
```

Author: vinay-deshmukh

libc/src/stdio/scanf_core/CMakeLists.txt

@@ -62,6 +62,7 @@ add_object_library(
     reader.h
   DEPENDS
     libc.src.__support.macros.attributes
+    libc.hdr.types.FILE
 )
 
 add_object_library(