make : fix CLBLAST compile support in FreeBSD (#2331)

* Fix Makefile for CLBLAST compile support and instructions for compile llama.cpp FreeBSD

* More general use-case for CLBLAST support (Linux and FreeBSD)

Author: yukiteruamano

Makefile

@@ -235,13 +235,15 @@ ggml-cuda.o: ggml-cuda.cu ggml-cuda.h
 endif # LLAMA_CUBLAS
 
 ifdef LLAMA_CLBLAST
-	CFLAGS   += -DGGML_USE_CLBLAST
-	CXXFLAGS += -DGGML_USE_CLBLAST
+
+	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
 

README.md

@@ -242,6 +242,23 @@ In order to build llama.cpp you have three different options.
     zig build -Doptimize=ReleaseFast
     ```
 
+-   Using `gmake` (FreeBSD):
+
+    1. Install and activate [DRM in FreeBSD](https://wiki.freebsd.org/Graphics)
+    2. Add your user to **video** group
+    3. Install compilation dependencies.
+
+        ```bash
+        sudo pkg install gmake automake autoconf pkgconf llvm15 clinfo clover \
+            opencl clblast openblas
+
+            gmake CC=/usr/local/bin/clang15 CXX=/usr/local/bin/clang++15 -j4
+        ```
+
+    **Notes:** With this packages you can build llama.cpp with OPENBLAS and
+    CLBLAST support for use OpenCL GPU acceleration in FreeBSD. Please read
+    the instructions for use and activate this options in this document below.
+
 ### Metal Build
 
 Using Metal allows the computation to be executed on the GPU for Apple devices: