1. Support user-provided values of CC, CFLAGS and LDFLAGS
2. Do not force the use of a static version of libsodium

--- a/Makefile
+++ b/Makefile
@@ -54,20 +54,20 @@
 endif
 
 # Compiler options
-CC       = gcc
+CC       := $(CC)
 # compiling flags here
-CFLAGS   = -g -std=c99 -I$(SRCDIR) -I$(LIBDIR)  -Wall -Wextra
+CFLAGS   := $(CFLAGS) -g -std=c99 -I$(SRCDIR) -I$(LIBDIR)  -Wall -Wextra
 ifndef MAC_OS
 	CFLAGS += $(shell pkg-config --cflags libsecret-1)
 endif
 TEST_CFLAGS = $(CFLAGS) -I.
 
 # Linker options
-LINKER   = gcc
+LINKER   := $(CC)
 ifdef MAC_OS
 LFLAGS   = -lsodium -largp
 else
-LFLAGS   = -l:libsodium.a -lseccomp
+LFLAGS   := $(LDFLAGS) -lsodium -lseccomp
 endif
 ifdef HAS_CJSON
 	LFLAGS += -lcjson