Use clang_getFileLocation instead of clang_getSpellingLocation

Both had the same behavior... until llvm/llvm-project@2e770ed
which fixed getSpellingLocation, but bindgen looks like it actually expects
the getFileLocation result.

bindgen/clang.rs

@@ -1608,7 +1608,7 @@ impl SourceLocation {
             let mut line = 0;
             let mut col = 0;
             let mut off = 0;
-            clang_getSpellingLocation(
+            clang_getFileLocation(
                 self.x, &mut file, &mut line, &mut col, &mut off,
             );
             (File { x: file }, line as usize, col as usize, off as usize)