Add test for gcc-5

This version should expose _Float128, but not other ts18661 types

Author: smowton

regression/ansi-c/gcc_version1/fake-gcc-5

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+gcc -Wno-macro-redefined -U __clang_major__ -D __GNUC__=5 -D __GNUC_MINOR__=0 -D __GNUC_PATCHLEVEL__=0 "$@"

regression/ansi-c/gcc_version1/gcc-5.c

@@ -0,0 +1,9 @@
+// These types should *not* be provided when emulating gcc-5:
+typedef float _Float32;
+typedef double _Float32x;
+typedef double _Float64;
+typedef long double _Float64x;
+typedef long double _Float128x;
+
+// But this type should:
+_Float128 f128;

regression/ansi-c/gcc_version1/test-gcc-5.desc

@@ -0,0 +1,7 @@
+CORE
+gcc-5.c
+--native-compiler ./fake-gcc-5
+^EXIT=0$
+^SIGNAL=0$
+--
+^CONVERSION ERROR$