This is a minmal fix by Michael Schwendt.
What upstream does in 1.1.6 is AC_SUBST(SPEEX_VERSION) in configure.ac,
which would require (autoreconf) during build.

diff -Nur speex-1.0.4-orig/speex.pc.in speex-1.0.4/speex.pc.in
--- speex-1.0.4-orig/speex.pc.in	2004-07-14 07:29:06.000000000 +0200
+++ speex-1.0.4/speex.pc.in	2004-10-18 03:46:48.475154816 +0200
@@ -7,7 +7,7 @@
 
 Name: speex
 Description: Speex is an audio codec tuned for speech
-Version: @SPEEX_VERSION@
+Version: @VERSION@
 Requires: ogg
 Conflicts:
 Libs: -L${libdir} -lspeex