If CC is defined at "ccache gcc", the expanded command ends up as:
env PATH=... CC=ccache gcc PYTHONPATH=... ./g-ir-scanner
causing compilation errors.
https://bugzilla.gnome.org/show_bug.cgi?id=690074
INTROSPECTION_SCANNER = \
env PATH=.libs:$(PATH) \
LPATH=.libs \
- CC=$(CC) \
+ CC="$(CC)" \
PYTHONPATH=$(top_builddir):$(top_srcdir) \
UNINSTALLED_INTROSPECTION_SRCDIR=$(top_srcdir) \
UNINSTALLED_INTROSPECTION_BUILDDIR=$(top_builddir) \