Add Eclipse Adoptium "Security Audit" suggested compiler options for jdk-21.0.3+ gcc builds

[andrew-m-leonard]

As part of the Eclipse Adoptium security audit, the following gcc options were suggested as being used to enhance the security of the JDK binaries.
Code generation suggestions:

• -fstack-protector-strong : Extends the basic stack protection without impacting all functions, see: https://lwn.net/Articles/584225/
• --param=ssp-buffer-size=4 : param The minimum size of buffers (i.e. arrays) that receive stack smashing protection when -fstack-protector is used. This ties in with -fstack-protector-strong to better cover the stack protection.

Compiler Warning suggestions:

• -Wformat : printf/scanf string checks
• -D_FORTIFY_SOURCE=2 : string related compile time checks
• -Wformat-security : enahnced printf/scanf string security checks
• -Wshadow : warn about variable/function shadowing
• -Wconversion : Warn for implicit conversions that may alter a value

[andrew-m-leonard]

@sxa fyi

[andrew-m-leonard]

dup of #3685