Fix SIGBUS on Apple Silicon in zlib_compress

Removes SAVE attribute from hash_table and hash_chain arrays in
deflate_compress subroutine. The SAVE attribute caused these large
arrays (32768 elements each) to be allocated as static data, which
triggered memory alignment issues on ARM64 processors resulting in
SIGBUS/EXC_BAD_ACCESS.

Making these arrays automatic allocation resolves the alignment
issue while maintaining identical functionality.

Fixes #1408

Author: krystophny

src/external/fortplot_zlib_core.f90

@@ -562,7 +562,6 @@ subroutine deflate_compress(input_data, input_len, output_data, output_len)
         ! Hash table for LZ77
         integer :: hash_table(0:HASH_SIZE-1)
         integer :: hash_chain(WINDOW_SIZE)
-        save :: hash_table, hash_chain
 
         ! Huffman tables (fixed Huffman for simplicity)
         integer :: literal_codes(0:285)