Support static compilation on Mac

Makefile

@@ -155,9 +155,28 @@ SOFTFLOAT_FLAGS  = -I $(SOFTFLOAT_INCDIR)
 SOFTFLOAT_LIBS   = $(SOFTFLOAT_LIBDIR)/softfloat.a
 SOFTFLOAT_SPECIALIZE_TYPE = RISCV
 
+UNAME_S := $(shell sh -c 'uname -s 2>/dev/null || echo not')
+
+STATIC_GMP_A :=
+STATIC_B_STATIC :=
+
+ifneq (,$(STATIC))
+    ifeq ($(UNAME_S),Darwin)
+        STATIC_GMP_A := 1
+    else
+        STATIC_B_STATIC := 1
+    endif
+endif
+
 GMP_FLAGS = $(shell pkg-config --cflags gmp)
-# N.B. GMP does not have pkg-config metadata on Ubuntu 18.04 so default to -lgmp
-GMP_LIBS = $(shell pkg-config --libs gmp || echo -lgmp)
+ifneq (,$(STATIC_GMP_A))
+    GMP_LIBS = $(shell pkg-config --variable=libdir gmp)/libgmp.a
+else
+    # N.B. GMP does not have pkg-config metadata on Ubuntu 18.04 so default to -lgmp
+    GMP_LIBS = $(shell pkg-config --libs gmp || echo -lgmp)
+endif
+
+# TODO: Remove Zlib when upgrading to Sail 0.19; it is no longer a requirement.
 ZLIB_FLAGS = $(shell pkg-config --cflags zlib)
 ZLIB_LIBS = $(shell pkg-config --libs zlib)
 
@@ -193,8 +212,9 @@ endif
 
 # Optional link C_LIBS statically. Unlike -static this will not
 # link glibc statically which is generally a bad idea.
-ifneq (,$(STATIC))
-    C_LIBS_WRAPPED = -Wl,-Bstatic $(C_LIBS) -Wl,-Bdynamic
+# Unfortunately the Mac linker does not support -Bstatic.
+ifneq (,$(STATIC_B_STATIC))
+    C_LIBS_WRAPPED = -Wl,--push-state,-Bstatic $(C_LIBS) -Wl,--pop-state
 else
     C_LIBS_WRAPPED = $(C_LIBS)
 endif