buildman: support newer gcc versions from kernel.org

Add support for gcc versions 7.3.0, 6.4.0 and 4.9.4.

Also use a regex for matching the tarball names. Some gcc versions
use '-ARCH-' instead of '_ARCH-'.

As part of this, we switch TravisCI to also using these toolchains for
all platforms.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/tools/buildman/toolchain.py b/tools/buildman/toolchain.py
index fb3157b..4b35f40 100644
--- a/tools/buildman/toolchain.py
+++ b/tools/buildman/toolchain.py
@@ -32,7 +32,7 @@
         HTMLParser.__init__(self)
         self.arch_link = None
         self.links = []
-        self._match = '_%s-' % arch
+        self.re_arch = re.compile('[-_]%s-' % arch)
 
     def handle_starttag(self, tag, attrs):
         if tag == 'a':
@@ -40,7 +40,7 @@
                 if tag == 'href':
                     if value and value.endswith('.xz'):
                         self.links.append(value)
-                        if self._match in value:
+                        if self.re_arch.search(value):
                             self.arch_link = value
 
 
@@ -430,7 +430,7 @@
         """
         arch = command.OutputOneLine('uname', '-m')
         base = 'https://www.kernel.org/pub/tools/crosstool/files/bin'
-        versions = ['4.9.0', '4.6.3', '4.6.2', '4.5.1', '4.2.4']
+        versions = ['7.3.0', '6.4.0', '4.9.4']
         links = []
         for version in versions:
             url = '%s/%s/%s/' % (base, arch, version)