https://bugs.gentoo.org/show_bug.cgi?id=454478

--- a/libpcre.pc.in	2011-12-28 17:57:58.000000000 +0100
+++ b/libpcre.pc.in	2013-03-11 13:45:42.120689738 +0100
@@ -9,4 +9,5 @@
 Description: PCRE - Perl compatible regular expressions C library with 8 bit character support
 Version: @PACKAGE_VERSION@
 Libs: -L${libdir} -lpcre
+Libs.private: -lpthread
 Cflags: -I${includedir} @PCRE_STATIC_CFLAG@