Fixup help text
--with-gcc overrides CC_STAGE0 when not cross-compiling (#8498)
Don't perform permission checks for scripts named with -ghci-script (#6017)

The user explicitly requested this script on the command-line, so it's
unnecessary to require that the script is also owned by the user.
Also, it is currently impossible to make a GHCi wrapper that invokes a
custom script without first making a copy of the script to circumvent
the permissions check, which seems wrong.
Include EXTRA_LD_OPTS (amongst other things) when linking programs

One problem was that we weren't including $1_$2_DIST_LD_OPTS when
linking a program, which looks to be accidental: it was being defined
but not used anywhere.  This meant that setting $1_$2_EXTRA_LD_OPTS,
for example, had no effect.

This commit straightens out the handling of LD_OPTS to be consistent
with the way we handle CC_OPTS and HC_OPTS.
Pass custom CC and LD opts to Cabal when configuring a package

Cabal compiles a program to check for the existence of foreign
libraries, so it needs to know our custom options, if any.
Include SRC_CC_OPTS and SRC_LD_OPTS when compiling ghc-cabal
Use LDFLAGS when compiling ghc-pwd
increase bounds for T3064