Use pkg-config for figuring python cflags and libs

Simplifies things a bit and also makes "PYTHON=python3 ./configure" work,
whereas it previously barfed on figuring the library names like
"libpython3.6m"

configure.ac

@@ -794,32 +794,15 @@ yes|no) ;;
 esac],
 [enable_python=no])
 
+WITH_PYTHON_SUBPACKAGE=0
 AS_IF([test "$enable_python" = yes],[
   AM_PATH_PYTHON([2.6],[
-    WITH_PYTHON_INCLUDE=`${PYTHON} -c 'from distutils.sysconfig import *; import sys; sys.stdout.write(get_python_inc())'`
-    WITH_PYTHON_SUBPACKAGE=1
-    save_CPPFLAGS="$CPPFLAGS"
-    CPPFLAGS="$CPPFLAGS -I$WITH_PYTHON_INCLUDE"
-    AC_CHECK_HEADER([Python.h],[],
-      [AC_MSG_ERROR([missing Python.h])
-      ])
-    CPPFLAGS="$save_CPPFLAGS"
-    save_LIBS="$LIBS"
-    AC_SEARCH_LIBS([Py_Main],[python${PYTHON_VERSION} python],[
-      WITH_PYTHON_LIB="$ac_res"
-    ],[AC_MSG_ERROR([missing python library])
-    ])
-    LIBS="$save_LIBS"
+    PKG_CHECK_MODULES([PYTHON], [python-${PYTHON_VERSION}], [WITH_PYTHON_SUBPACKAGE=1])
+    AC_SUBST(PYTHON_CFLAGS)
+    AC_SUBST(PYTHON_LIB)
   ])
-],[
-    WITH_PYTHON_INCLUDE=
-    WITH_PYTHON_LIB=
-    WITH_PYTHON_SUBPACKAGE=0
 ])
 
-AC_SUBST(WITH_PYTHON_INCLUDE)
-AC_SUBST(WITH_PYTHON_LIB)
-
 AM_CONDITIONAL(ENABLE_PYTHON,[test "$WITH_PYTHON_SUBPACKAGE" = 1])
 
 AC_PATH_PROG(DOXYGEN, doxygen, no)

python/Makefile.am

@@ -7,7 +7,7 @@ EXTRA_DIST = rpm/__init__.py rpm/transaction.py
 
 AM_CPPFLAGS = -I$(top_builddir)/include/
 AM_CPPFLAGS += -I$(top_srcdir)/python
-AM_CPPFLAGS += -I@WITH_PYTHON_INCLUDE@
+AM_CPPFLAGS += @PYTHON_CFLAGS@
 
 pkgpyexec_LTLIBRARIES = _rpm.la _rpmb.la _rpms.la
 pkgpyexec_DATA = rpm/__init__.py rpm/transaction.py
@@ -16,7 +16,7 @@ _rpm_la_LDFLAGS = -module -avoid-version -shared
 _rpm_la_LIBADD = \
 	$(top_builddir)/lib/librpm.la \
 	$(top_builddir)/rpmio/librpmio.la \
-	@WITH_PYTHON_LIB@
+	@PYTHON_LIBS@
 
 _rpm_la_SOURCES = rpmmodule.c rpmsystem-py.h \
 	header-py.c header-py.h \
@@ -40,7 +40,7 @@ _rpmb_la_LIBADD = \
 	$(top_builddir)/build/librpmbuild.la \
 	$(top_builddir)/lib/librpm.la \
 	$(top_builddir)/rpmio/librpmio.la \
-	@WITH_PYTHON_LIB@
+	@PYTHON_LIBS@
 
 _rpmb_la_SOURCES = rpmbmodule.c rpmsystem-py.h \
 	spec-py.c spec-py.h
@@ -50,7 +50,7 @@ _rpms_la_LIBADD = \
         $(top_builddir)/sign/librpmsign.la \
         $(top_builddir)/lib/librpm.la \
         $(top_builddir)/rpmio/librpmio.la \
-        @WITH_PYTHON_LIB@
+	@PYTHON_LIBS@
 
 _rpms_la_SOURCES = rpmsmodule.c rpmsystem-py.h