refactor: rename PIP_NO_\* to PIP_HAS_\* with inverted logic

All feature flags now use positive naming (enabled by default):
- PIP_HAS_FILESYSTEM, PIP_HAS_THREADS, PIP_HAS_SOCKET
- PIP_HAS_PROCESS, PIP_HAS_DYNLIB, PIP_HAS_FFT, PIP_HAS_SERIAL

Preprocessor guards inverted:
- #ifndef PIP_NO_X → #ifdef PIP_HAS_X
- #ifdef PIP_NO_X → #ifndef PIP_HAS_X

CMake options default ON instead of OFF.
Platform blocks set flags OFF to disable features.

85 files transformed via Python script + 2 manual fixes.

libs/main/io_devices/pifile.cpp

@@ -17,7 +17,7 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#ifndef PIP_NO_FILESYSTEM
+#ifdef PIP_HAS_FILESYSTEM
 #  include "pifile.h"
 
 #  include "pidir.h"
@@ -46,7 +46,7 @@
 #	include <utime.h>
 #  endif
 #  define S_IFHDN 0x40
-#  if defined(QNX) || defined(ANDROID) || defined(PIP_NO_FILESYSTEM)
+#  if defined(QNX) || defined(ANDROID) || !defined(PIP_HAS_FILESYSTEM)
 #	define _fopen_call_  fopen
 #	define _fseek_call_  fseek
 #	define _ftell_call_  ftell
@@ -538,7 +538,7 @@ PIFile::FileInfo PIFile::fileInfo(const PIString & path) {
 	ret.time_modification = PIDateTime::fromSystemTime(PISystemTime(fs.MTIME.tv_sec, fs.MTIME.tv_nsec));
 #	  endif
 #	endif
-#	ifndef PIP_NO_FILESYSTEM
+#	ifdef PIP_HAS_FILESYSTEM
 	ret.perm_user         = FileInfo::Permissions((mode & S_IRUSR) == S_IRUSR, (mode & S_IWUSR) == S_IWUSR, (mode & S_IXUSR) == S_IXUSR);
 	ret.perm_group        = FileInfo::Permissions((mode & S_IRGRP) == S_IRGRP, (mode & S_IWGRP) == S_IWGRP, (mode & S_IXGRP) == S_IXGRP);
 	ret.perm_other        = FileInfo::Permissions((mode & S_IROTH) == S_IROTH, (mode & S_IWOTH) == S_IWOTH, (mode & S_IXOTH) == S_IXOTH);
@@ -636,4 +636,4 @@ int PIFile::writeAll(const PIString & path, const PIByteArray & data) {
 	f.clear();
 	return f.write(data.data(), data.size_s());
 }
-#endif // PIP_NO_FILESYSTEM
+#endif // PIP_HAS_FILESYSTEM