Add explicit gcc-c++ BuildRequires to fix build

gcc-c++ has been removed from default buildroot package set.

pstoedit.spec

@@ -1,6 +1,6 @@
 Name:           pstoedit
 Version:        3.73
-Release:        2%{?dist}
+Release:        3%{?dist}
 Summary:        Translates PostScript and PDF graphics into other vector formats
 
 Group:          Applications/Productivity
@@ -18,6 +18,7 @@ BuildRequires:  dos2unix
 BuildRequires:  ghostscript
 BuildRequires:  plotutils-devel
 BuildRequires:  automake
+BuildRequires:  gcc-c++
 %ifnarch ia64
 BuildRequires:  libEMF-devel
 %endif
@@ -87,6 +88,10 @@ find $RPM_BUILD_ROOT -type f -name "*.la" -exec rm -f {} ';'
 
 
 %changelog
+* Tue Jul 24 2018 Sebastian Kisela <skisela@redhat.com> - 3.73-3
+- Add explicit gcc-c++ BuildRequires, as it has been removed from
+the buildroot default packages set.
+
 * Fri Jul 13 2018 Fedora Release Engineering <releng@fedoraproject.org> - 3.73-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_29_Mass_Rebuild