Revert "Add pffft to manifest"

This reverts commit e9a3378679175a8c2d49eef906c72f292f01815a.

Reason: broke the build

Bug: 158129386
Change-Id: I6d453d1894d1b967a3e7f8bf699a86bb3009fc35
diff --git a/default.xml b/default.xml
index 70121d9..19fe9a1 100644
--- a/default.xml
+++ b/default.xml
@@ -328,7 +328,6 @@
   <project path="external/OpenCSD" name="platform/external/OpenCSD" groups="pdk" />
   <project path="external/oss-fuzz" name="platform/external/oss-fuzz" groups="pdk" />
   <project path="external/owasp/sanitizer" name="platform/external/owasp/sanitizer" groups="pdk" />
-  <project path="external/pffft" name="platform/external/pffft" groups="pdk" />
   <project path="external/parameter-framework" name="platform/external/parameter-framework" groups="pdk" />
   <project path="external/pcre" name="platform/external/pcre" groups="pdk" />
   <project path="external/pdfium" name="platform/external/pdfium" groups="pdk" />