PET not installing pet.pc pkgconfig files

[Emil Vatai]

After running

```

./get_submodules.sh
./autogen.sh
./configure   --enable-shared  --prefix="myprefixdir"

make -j
make -j install
```

I expect to find a pet.pc (somewhere) inside myprefixdir (probably in myprefixdir/lib/pkgconfig) but there is none.

Best,

E

[Emil Vatai]

This patch seems to do the trick:

```
diff --git a/Makefile.am b/Makefile.am
index 56cb1fa..a924412 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -176,5 +176,8 @@ dist-hook: isl.py
  cp $< $(distdir)/
  echo @GIT_HEAD_VERSION@ > $(distdir)/GIT_HEAD_ID
 
+pkgconfigdir=$(pkgconfig_libdir)
+pkgconfig_DATA = $(pkgconfig_libfile)
+
 gitversion.h: @GIT_HEAD@
  $(AM_V_GEN)echo '#define GIT_HEAD_ID "'@GIT_HEAD_VERSION@'"' > $@
```