Libguestfs - May 2019 - [PATCH] python: PYTHON_LIBS is not set in Python 3.8 (RHBZ#1705482).

Python 3.8 no longer links C extensions to -lpython, instead relying
on the fact that the python binary itself already contains those
symbols.  This means $PYTHON_LIBS is empty and so the Python bindings
are not built.

Use a different test to see if the python module is available.
---
 m4/guestfs-python.m4 | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/m4/guestfs-python.m4 b/m4/guestfs-python.m4
index 7d4c991bb..befa9b102 100644
--- a/m4/guestfs-python.m4
+++ b/m4/guestfs-python.m4
@@ -33,14 +33,17 @@ AS_IF([test "x$enable_python" !=
"xno"],[
         PYTHON_VERSION_MINOR=`$PYTHON -c "import sys; print
(sys.version_info@<:@1@:>@)"`
         PYTHON_VERSION="$PYTHON_VERSION_MAJOR.$PYTHON_VERSION_MINOR"
 	AC_MSG_RESULT([$PYTHON_VERSION])
+
         # Debian: python-2.7.pc, python-3.2.pc
         PKG_CHECK_MODULES([PYTHON], [python-"$PYTHON_VERSION"],[
+            have_python_module=1
             AC_SUBST([PYTHON_CFLAGS])
             AC_SUBST([PYTHON_LIBS])
             AC_SUBST([PYTHON_VERSION])
             AC_DEFINE([HAVE_PYTHON],[1],[Python library found at compile time])
         ],[
             PKG_CHECK_MODULES([PYTHON], [python],[
+                have_python_module=1
                 AC_SUBST([PYTHON_CFLAGS])
                 AC_SUBST([PYTHON_LIBS])
                 AC_SUBST([PYTHON_VERSION])
@@ -49,6 +52,7 @@ AS_IF([test "x$enable_python" != "xno"],[
                 AC_MSG_WARN([python $PYTHON_VERSION not found])
             ])
         ])
+
         AC_MSG_CHECKING([Python prefix])
         PYTHON_PREFIX=`$PYTHON -c "import sys; print (sys.prefix)"`
         AC_MSG_RESULT([$PYTHON_PREFIX])
@@ -101,4 +105,4 @@ AS_IF([test "x$enable_python" !=
"xno"],[
     AC_SUBST(PYTHON_EXT_SUFFIX)
 ])
 AM_CONDITIONAL([HAVE_PYTHON],
-    [test "x$PYTHON" != "xno" && test
"x$PYTHON_LIBS" != "x" ])
+    [test "x$PYTHON" != "xno" && test
"x$have_python_module" = "x1" ])
-- 
2.21.0