DevKit build support fixes for later OS versions

[andrew-m-leonard]

Attempting to build the Linux DevKit on Fedora38, or RHEL9, has the following issues:

• Makefile uses uname -p, which returns "" or unknown om some OS's, should perhaps be changed to uname -m upstream: https://github.com/openjdk/jdk21u/blob/a0b3c6cd86861a038a7b7967428266c882bd5d7a/make/devkit/Makefile#L61
• Tools.gmk.patch does not download the NOARCH GPG Centos keys, thus GPG verify fails if the local OS does not already have the keys
• Building on Fedora required gcc build option --without-isl, needs some investigation ?