Pass -DFMT_HEADER_ONLY as a compiler flag

Moving the definition of the FMT_HEADER_ONLY macro from a file to the
compiler makes all code relying on this macro independent of a single
file

Also cleanup some unused fmt includes

CMakeLists.txt

@@ -131,6 +131,7 @@ target_compile_definitions(btop PRIVATE
   _GLIBCXX_ASSERTIONS _LIBCPP_ENABLE_ASSERTIONS=1
   # Only has an effect with optimizations enabled
   $<$<NOT:$<CONFIG:Debug>>:_FORTIFY_SOURCE=2>
+  FMT_HEADER_ONLY
 )
 
 # Enable GPU support

Makefile

@@ -183,7 +183,7 @@ override GOODFLAGS := $(foreach flag,$(TESTFLAGS),$(strip $(shell echo "int main
 override REQFLAGS   := -std=c++20
 WARNFLAGS			:= -Wall -Wextra -pedantic
 OPTFLAGS			:= -O2 -ftree-vectorize -flto=$(LTO)
-LDCXXFLAGS			:= -pthread -D_FORTIFY_SOURCE=2 -D_GLIBCXX_ASSERTIONS -D_FILE_OFFSET_BITS=64 $(GOODFLAGS) $(ADDFLAGS)
+LDCXXFLAGS			:= -pthread -DFMT_HEADER_ONLY -D_FORTIFY_SOURCE=2 -D_GLIBCXX_ASSERTIONS -D_FILE_OFFSET_BITS=64 $(GOODFLAGS) $(ADDFLAGS)
 override CXXFLAGS	+= $(REQFLAGS) $(LDCXXFLAGS) $(OPTFLAGS) $(WARNFLAGS)
 override LDFLAGS	+= $(LDCXXFLAGS) $(OPTFLAGS) $(WARNFLAGS)
 INC					:= $(foreach incdir,$(INCDIRS),-isystem $(incdir)) -I$(SRCDIR)

src/btop_log.cpp

@@ -9,6 +9,7 @@
 #include <string_view>
 
 #include <fmt/core.h>
+#include <fmt/ostream.h>
 
 #include "btop_shared.hpp"
 #include "btop_tools.hpp"

src/btop_tools.hpp

@@ -38,11 +38,9 @@ tab-size = 4
 		#define HOST_NAME_MAX 64
 	#endif
 #endif
-#define FMT_HEADER_ONLY
+
 #include "fmt/core.h"
-#include "fmt/format.h"
 #include "fmt/ostream.h"
-#include "fmt/ranges.h"
 
 using std::array;
 using std::atomic;