Drop unneeded pth-devel dependencies

It's not checked on build-time and it seems only needed for macro
so target application must depend on pth-devel. And what's more
important, we need to support npth-devel, so we shouldn't require
both.

Which gets us back to the point that it is just wrong requiring
(n)pth-devel from libassuan.

Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>

libassuan.spec

@@ -1,7 +1,7 @@
 Name:    libassuan
 Summary: GnuPG IPC library
 Version: 2.4.3
-Release: 4%{?dist}
+Release: 5%{?dist}
 
 # The library is LGPLv2+, the documentation GPLv3+
 License: LGPLv2+ and GPLv3+
@@ -14,7 +14,6 @@ Patch1:  libassuan-2.1.0-multilib.patch
 
 BuildRequires: gawk
 BuildRequires: libgpg-error-devel >= 1.8
-BuildRequires: pth-devel
 
 %description
 This is the IPC library used by GnuPG 2, GPGME and a few other
@@ -25,7 +24,6 @@ Summary: GnuPG IPC library
 Group: Development/Libraries
 Provides: libassuan2-devel = %{version}-%{release}
 Provides: libassuan2-devel%{?_isa} = %{version}-%{release}
-Requires: pth-devel
 Requires: libassuan%{?_isa} = %{version}-%{release}
 Requires(post): /sbin/install-info
 Requires(preun): /sbin/install-info
@@ -91,6 +89,9 @@ fi
 
 
 %changelog
+* Mon Aug 07 2017 Igor Gnatenko <ignatenkobrain@fedoraproject.org> - 2.4.3-5
+- Drop unneeded pth-devel dependencies
+
 * Thu Aug 03 2017 Fedora Release Engineering <releng@fedoraproject.org> - 2.4.3-4
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_27_Binutils_Mass_Rebuild