bzip: Precompile common expensive headers

Utilities/cmbzip2/CMakeLists.txt

@@ -19,3 +19,7 @@ endif()
 add_definitions(-D_FILE_OFFSET_BITS=64)
 add_library(cmbzip2
   blocksort.c huffman.c crctable.c randtable.c compress.c decompress.c bzlib.c)
+
+if(WIN32 AND CMake_BUILD_PCH)
+  target_precompile_headers(cmbzip2 PRIVATE "bzlib.h")
+endif()