Remove unused project external/fmtlib.

Bug: N/A
Test: builds
Merged-In: I5b0c5323fc749a0ddc07b37f882130d8b39b15e9
Change-Id: I5b0c5323fc749a0ddc07b37f882130d8b39b15e9

default.xml

@@ -150,7 +150,6 @@
   <project path="external/flac" name="platform/external/flac" groups="pdk" />
   <project path="external/flatbuffers" name="platform/external/flatbuffers" groups="pdk" />
   <project path="external/fonttools" name="platform/external/fonttools" groups="pdk-fs" />
-  <project path="external/fmtlib" name="platform/external/fmtlib" groups="pdk" />
   <project path="external/freetype" name="platform/external/freetype" groups="pdk" />
   <project path="external/fsck_msdos" name="platform/external/fsck_msdos" groups="pdk-cw-fs,pdk-fs" />
   <project path="external/gemmlowp" name="platform/external/gemmlowp" groups="pdk" />