At line 150 of pkg-config.1 there is a macro inappropriately starting in column 1:

    150 \fI.pc\fP files. Most packages define the variable "prefix", for

This is garbling subsequent page headers:

friggms:src$ nroff -man pkg-config.1 | egrep 'Page|1\).\).\).\)$'
     pkg-config(1)                                       pkg-config(1)
     Page 1                                          (printed 10/5/08)
     pkg-config(1)                                       pkg-config(1)
     Page 2                                          (printed 10/5/08)
     pkg-config(1)                                       pkg-config(1)
     Page %                                          (printed 10/5/08)
     pkg-con4ig(1)                                       pkg-con4ig(1)
     Page %                                          (printed 10/5/08)
     pkg-con5ig(1)                                       pkg-con5ig(1)
<snip>

This is easily fixed by avoiding the \fI in column 1, for instance by moving the last any from line 149 to line 150:

This sets a global value for a variable, overriding the value in
any \fI.pc\fP files. Most packages define the variable "prefix", for