Initialize some variables to avoid gcc warning

GCC cannot follow the logic that determines if it's safe to free
lrhs in expr.c.  Initializing these variables to NULL silences
this warning.

Resolves: #1799619

ltrace-0.7.91-rh1799619.patch

@@ -0,0 +1,16 @@
+diff -rup a/expr.c b/expr.c
+--- a/expr.c	2013-10-10 08:43:55.000000000 -0400
++++ b/expr.c	2020-02-06 17:05:40.658679755 -0500
+@@ -189,10 +189,10 @@ int
+ expr_clone(struct expr_node *retp, const struct expr_node *node)
+ {
+ 	*retp = *node;
++	struct expr_node *nlhs;
++	struct expr_node *nrhs = NULL;
+ 
+ 	switch (node->kind) {
+-		struct expr_node *nlhs;
+-		struct expr_node *nrhs;
+ 
+ 	case EXPR_OP_ARGNO:
+ 	case EXPR_OP_SELF:

ltrace.spec

@@ -1,7 +1,7 @@
 Summary: Tracks runtime library calls from dynamically linked executables
 Name: ltrace
 Version: 0.7.91
-Release: 36%{?dist}
+Release: 37%{?dist}
 URL: http://ltrace.alioth.debian.org/
 License: GPLv2+
 
@@ -123,6 +123,9 @@ Patch33: ltrace-0.7.91-testsuite-system_call_params.patch
 # Ignore bogus files from the environment
 Patch34: ltrace-0.7.91-XDG_CONFIG_DIRS.patch
 
+# GCC erroneously warns about uninitialized values
+Patch35: ltrace-0.7.91-rh1799619.patch
+
 %description
 Ltrace is a debugging program which runs a specified command until the
 command exits.  While the command is executing, ltrace intercepts and
@@ -169,6 +172,7 @@ execution of processes.
 %patch32 -p1
 %patch33 -p1
 %patch34 -p1
+%patch35 -p1
 
 %build
 autoreconf -i
@@ -196,6 +200,9 @@ echo ====================TESTING END=====================
 %{_datadir}/ltrace
 
 %changelog
+* Thu Feb  6 2020 DJ Delorie <dj@redhat.com> - 0.7.91-37
+- Initialize some variables to avoid gcc warning (#1799619)
+
 * Wed Jan 29 2020 Fedora Release Engineering <releng@fedoraproject.org> - 0.7.91-36
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_32_Mass_Rebuild