Summary: Compile fdlibm with -O3 and relevant C flags on gcc arches.
Reviewed-by: mbaesken, andrew

Reviewed-by: shade

Reviewed-by: jwilhelm

8073139: PPC64: User-visible arch directory and os.arch value on ppc64le cause issues with Java tooling
Reviewed-by: erikj, goetz, dholmes

Summary: Generate debug info for assembler files as needed.
Reviewed-by: erikj

Reviewed-by: erikj

Reviewed-by: erikj

Summary: reapply JDK- 8187045 changes to flags.m4
Reviewed-by: tbell, erikj

Reviewed-by: ihse, kevinw

Reviewed-by: erikj, ihse, ddehaven, billyh

Reviewed-by: erikj, ihse

Reviewed-by: ihse, henryjen, erikj