build-many-glibcs.py: Do not build C++ PCHs by default

They are not used during the subsequent glibc build, so creating them
merely wastes time.

diff --git a/scripts/build-many-glibcs.py b/scripts/build-many-glibcs.py
index 193d49727bf480a400b5c0e1a8096629dbc62e9a..92cc613c5d8dc188918a394de52a3fedbf975695 100755 (executable)
--- a/scripts/build-many-glibcs.py
+++ b/scripts/build-many-glibcs.py
@@ -1382,9 +1382,12 @@ class Config(object):
         else:
             tool_build = 'gcc'
             # libsanitizer commonly breaks because of glibc header
-            # changes, or on unusual targets.
+            # changes, or on unusual targets.  C++ pre-compiled
+            # headers are not used during the glibc build and are
+            # expensive to create.
             if not self.ctx.full_gcc:
-                cfg_opts += ['--disable-libsanitizer']
+                cfg_opts += ['--disable-libsanitizer',
+                             '--disable-libstdcxx-pch']
             langs = 'all' if self.ctx.full_gcc else 'c,c++'
             cfg_opts += ['--enable-languages=%s' % langs,
                          '--enable-shared', '--enable-threads']