Attempt to handle decompression error on some broken PDF files

from times to times we go through files where no text is detected, while readers
like evince reads the pdf nicely. After digging it occured this is because the
PDF includes some badly compressed data. This may be fixed by uncompressing byte
per byte and ignoring the error on the last check bytes (arbitrarily found to be
the 3 last).

This has been largely inspired by py-pdf/pypdf#422
and the test file has been taken from there, so credits to @zegrep.

pdfminer/pdftypes.py

@@ -187,7 +187,10 @@ def stream_value(x):
 
 
 def decompress_corrupted(data):
-    d = zlib.decompressobj(zlib.MAX_WBITS | 32)
+    """Called on some data that can't be properly decoded because of CRC checksum
+    error. Attempt to decode it skipping the CRC.
+    """
+    d = zlib.decompressobj()
     f = io.BytesIO(data)
     result_str = b''
     buffer = f.read(1)
@@ -198,6 +201,7 @@ def decompress_corrupted(data):
             buffer = f.read(1)
             i += 1
     except zlib.error:
+        # Let the error propagates if we're not yet in the CRC checksum
         if i < len(data) - 3:
             raise
     return result_str