Enable BTLS for Centos 6

REQUIRED CHANGES TO MOCK CONFIG:
--- /etc/mock/epel-6-i386.cfg	2018-03-05 13:02:10.641094606 -0500
+++ /etc/mock/epel-6-i386-preview.cfg	2018-03-19 14:23:09.737226304 -0400
@@ -1,7 +1,7 @@
 config_opts['root'] = 'epel-6-i386'
 config_opts['target_arch'] = 'i686'
 config_opts['legal_host_arches'] = ('i386', 'i586', 'i686', 'x86_64')
-config_opts['chroot_setup_cmd'] = 'install @buildsys-build'
+config_opts['chroot_setup_cmd'] = 'install @buildsys-build devtoolset-2-build'
 config_opts['dist'] = 'el6'  # only useful for --resultdir variable subst
 # beware: RHEL use 6Server or 6Client
 config_opts['releasever'] = '6'
@@ -69,4 +61,14 @@
 mirrorlist=http://mirrors.fedoraproject.org/mirrorlist?repo=epel-debug-6&arch=i386
 failovermethod=priority
 enabled=0
+
+[devtoolset]
+Name=Scientific Linux devtoolset - $basearch
+baseurl=http://ftp.scientificlinux.org/linux/scientific/6x/external_products/devtoolset/$basearch/
+        http://ftp1.scientificlinux.org/linux/scientific/6x/external_products/devtoolset/$basearch/
+        http://ftp2.scientificlinux.org/linux/scientific/6x/external_products/devtoolset/$basearch/
+
+enabled=1
+gpgcheck=1
+gpgkey=file:///etc/pki/mock/RPM-GPG-KEY-sl file:///etc/pki/mock/RPM-GPG-KEY-sl6
 """

MANUALLY ADD TO /etc/pki/mock on host:
http://ftp.scientificlinux.org/linux/scientific/6x/i386/os/RPM-GPG-KEY-sl
http://ftp.scientificlinux.org/linux/scientific/6x/i386/os/RPM-GPG-KEY-sl6

mono-core.spec

@@ -16,7 +16,6 @@
 # Please submit bugfixes or comments via http://bugzilla.xamarin.com/
 #
 
-
 %if 0%{?fedora} || 0%{?rhel} || 0%{?centos}
 %define ext_man .gz
 %else
@@ -24,6 +23,9 @@
 %endif
 %define llvm no
 %global debug_package %{nil}
+%global _enable_debug_package %{nil}
+%global __debug_install_post %{nil}
+%global __debug_package %{nil}
 %define sgen yes
 
 Name:           mono-core
@@ -44,6 +46,9 @@ BuildRequires:  cmake
 BuildRequires:  gettext
 BuildRequires:  fdupes
 BuildRequires:  gcc-c++
+%if 0%{?rhel} < 7
+BuildRequires:  devtoolset-2-gcc-c++
+%endif
 BuildRequires:  libgdiplus-devel
 BuildRequires:  libtool
 %if 0%{?fedora} || 0%{?rhel} || 0%{?centos}
@@ -133,6 +138,7 @@ technologies that have been submitted to the ECMA for standardization.
 %setup -q -n mono-%{version}
 
 %build
+%{?scl:scl enable %{scl} - << \EOF}
 ./autogen.sh
 # These are only needed if there are patches to the runtime
 #rm -f libgc/libtool.m4
@@ -164,6 +170,7 @@ export PATH=/opt/novell/llvm-mono/bin:$PATH
   --with-ikvm=yes \
   --with-moonlight=no
 make
+%{?scl:EOF}
 
 %install
 %make_install
@@ -265,9 +272,7 @@ rm %{buildroot}%{_bindir}/mono-sgen-gdb.py
 %{_bindir}/setreg
 %{_bindir}/sn
 %{_libdir}/libMonoPosixHelper.so*
-%if 0%{?rhel} >= 7
 %{_libdir}/libmono-btls-shared.so*
-%endif
 %{_libdir}/libikvm-native.so
 %{_mandir}/man1/cert-sync.1%ext_man
 %{_mandir}/man1/certmgr.1%ext_man
@@ -323,9 +328,7 @@ rm %{buildroot}%{_bindir}/mono-sgen-gdb.py
 %{_prefix}/lib/mono/4.5/Microsoft.CodeAnalysis.VisualBasic.dll*
 %{_prefix}/lib/mono/4.5/Microsoft.CSharp.dll
 %{_prefix}/lib/mono/4.5/Microsoft.VisualC.dll
-%if 0%{?rhel} >= 7
 %{_prefix}/lib/mono/4.5/Mono.Btls.Interface.dll
-%endif
 %{_prefix}/lib/mono/4.5/Mono.CSharp.dll
 %{_prefix}/lib/mono/4.5/Mono.Cairo.dll
 %{_prefix}/lib/mono/4.5/Mono.CompilerServices.SymbolWriter.dll
@@ -378,9 +381,7 @@ rm %{buildroot}%{_bindir}/mono-sgen-gdb.py
 %{_prefix}/lib/mono/gac/ICSharpCode.SharpZipLib
 %{_prefix}/lib/mono/gac/Microsoft.CSharp
 %{_prefix}/lib/mono/gac/Microsoft.VisualC
-%if 0%{?rhel} >= 7
 %{_prefix}/lib/mono/gac/Mono.Btls.Interface
-%endif
 %{_prefix}/lib/mono/gac/Mono.CSharp
 %{_prefix}/lib/mono/gac/Mono.Cairo
 %{_prefix}/lib/mono/gac/Mono.Cecil