Add ccache and f90cache as standard spkgs

[ohanar]

This is needed to eliminate build time when switching between various branches in the git based workflow.

Installation:

• Install dependencies
• Add the spkg ​http://wstein.org/home/ohanar/spkgs/ccache-3.1.7.spkg to spkg/standard
• Add the spkg ​http://wstein.org/home/ohanar/spkgs/f90cache-0.93.7.spkg to spkg/standard
• Apply attachment:trac13032_root.patch​ to the root repository
• Apply attachment:trac13032_doc.patch​ to the sage library

[ohanar]

Not yet ready, the build scripts still need to be modified to set CC and CXX once this is installed.

[ppurka]

Two general comments:

1. We probably need to set the max cache size. On my system the default is 1G, which some people may dislike. It can be set using ccache -M <size>{G,M,K}, where the letters G, M, K can be used to specify the usual gigabytes, megabytes and kilobytes. This needs to be set only if CCACHE_DIR is empty, since the user may have his/her own ccache settings.
2. This fact about the ccache size should be mentioned in the documentation, so that the user knows how much of disk space will be used.

[ohanar]

Replying to ppurka:

Two general comments:

1. We probably need to set the max cache size. On my system the default is 1G, which some people may dislike. It can be set using ccache -M <size>{G,M,K}, where the letters G, M, K can be used to specify the usual gigabytes, megabytes and kilobytes.

This is set in the spkg-install to 3G.

This needs to be set only if CCACHE_DIR is empty, since the user may have his/her own ccache settings.

2. This fact about the ccache size should be mentioned in the documentation, so that the user knows how much of disk space will be used.

Both good points, I'll see about changing these.