feat(build): add JERBOA_CC_OPT env var to control cc optimization level

ober

399ed5cbd32753fa81b37d393c08fd8a9e91d376

diff --git a/support/build-jerboa-multicall.ss b/support/build-jerboa-multicall.ss
index 7f3b391..63deecb 100644
--- a/support/build-jerboa-multicall.ss
+++ b/support/build-jerboa-multicall.ss
@@ -1672,9 +1672,10 @@
          (map (lambda (a) (if (file-exists? (format "~a/~a" csv-dir a)) (format " ~a/~a" csv-dir a) ""))
               '("liblz4.a" "libz.a"))))
 (define cc (env "CC" "cc"))
-(run (format "~a -I~a -I~a -O2~a -o ~a ~a/support/multicall-main.c ~a/libkernel.a~a~a ~a"
-             cc (shell-quote build-dir) (shell-quote csv-dir)
-             harden-cflags (shell-quote output)
+(define cc-opt (env "JERBOA_CC_OPT" "-O2"))
+(run (format "~a -I~a -I~a ~a~a -o ~a ~a/support/multicall-main.c ~a/libkernel.a~a~a ~a"
+              cc (shell-quote build-dir) (shell-quote csv-dir)
+              cc-opt harden-cflags (shell-quote output)
              (shell-quote repo) (shell-quote csv-dir) extra-archives harden-ldflags os-libs))
 
 (printf "==> [6/6] symlinks~n")