Update library detection regex for FFmpeg and PortAudio

Refined the detection logic for FFmpeg to use a case-insensitive regex and simplified the PortAudio regex to match 'portaudio_x86' or 'portaudio_x64' more concisely.

Author: DosX-dev

db/PE/FFmpeg.4.sg

@@ -5,7 +5,7 @@
 meta("library", "FFmpeg");
 
 function detect() {
-    if (PE.isLibraryPresent("ffmpeg.dll")) {
+    if (PE.isLibraryPresentExp(/ffmpeg/i)) {
         bDetected = true;
     }
 

db/PE/PortAudio.4.sg

@@ -5,7 +5,7 @@
 meta("library", "PortAudio");
 
 function detect() {
-    if (PE.isLibraryPresentExp(/^(portaudio_x86|portaudio_x64)/i)) {
+    if (PE.isLibraryPresentExp(/^portaudio_x(86|64)/i)) {
         bDetected = true;
     }