Build: fix amalgamation public header warning

The previous code would mix up absolute and relative paths to determine
when to print the warning about public headers first being encountered
when processing the source files. This commit fixes this and thus gets
rid of the incorrect warnings.

Author: athre0z

assets/amalgamate.py

@@ -59,11 +59,11 @@ def merge_headers(
     with path.open() as f:
         lines = [x.rstrip() for x in f]
 
-    if path in covered_headers:
+    if header in covered_headers:
         return []
 
     print(f'Processing header "{header}"')
-    covered_headers.add(path)
+    covered_headers.add(header)
 
     # Print the header we emit next & the include stack (if non-root).
     include_stack = []
@@ -169,8 +169,6 @@ def main():
             stack=[],
         )))
 
-    print(covered_headers)
-
     with open(OUTPUT_DIR / 'Zydis.c', 'w') as f:
         f.write('\n'.join(FILE_HEADER + merge_sources(
             source_dir=ZYDIS_ROOT / 'src',