Fixes for CLBLAST compile support in FreeBSD

[yukiteruamano]

Hi, this PR has two fixes:

1. New bits in Makefile for add CLBLAST support in FreeBSD.
2. Instructions for compile llama.cpp in FreeBSD using gmake. These instructions have the packages necessary for OpenBLAS and CLBLAST support for llama.cpp. These packages are available and up-to-date from FreeBSD 11 to FreeBSD 13 in almost architectures supported (only aarch64 remain with lagged support).

All tested in FreeBSD 13.2, local compilation and testing without issues.

[cebtenzzre]

Why don't we just use pkg-config --cflags clblast OpenCL and pkg-config --libs clblast OpenCL on *BSD and Linux? Some of this special-casing seems unnecessary to me.

[yukiteruamano]

Why don't we just use pkg-config --cflags clblast OpenCL and pkg-config --libs clblast OpenCL on *BSD and Linux? Some of this special-casing seems unnecessary to me.

This is possible, the diff code is

diff --git a/Makefile b/Makefile
index 4782096..e620835 100644
--- a/Makefile
+++ b/Makefile
@@ -236,20 +236,14 @@ endif # LLAMA_CUBLAS

 ifdef LLAMA_CLBLAST

-       # If FreeBSD system is detected and env GGML_USE_CLBLAST=1 is used, we compile llama.cpp with this support
-       ifeq ($(UNAME_S),FreeBSD)
-               CFLAGS   += -DGGML_USE_CLBLAST $(shell pkg-config --cflags clblast)
-               CXXFLAGS += -DGGML_USE_CLBLAST $(shell pkg-config --cflags clblast)
-       else
-               CFLAGS   += -DGGML_USE_CLBLAST
-               CXXFLAGS += -DGGML_USE_CLBLAST
-       endif
+       CFLAGS   += -DGGML_USE_CLBLAST $(shell pkg-config --cflags clblast OpenCL)
+       CXXFLAGS += -DGGML_USE_CLBLAST $(shell pkg-config --cflags clblast OpenCL)

        # Mac provides OpenCL as a framework
        ifeq ($(UNAME_S),Darwin)
                LDFLAGS += -lclblast -framework OpenCL
        else
-               LDFLAGS += -lclblast -lOpenCL
+               LDFLAGS += $(shell pkg-config --libs clblast OpenCL)
        endif
        OBJS    += ggml-opencl.o