Add the possibility to set global compile time settings (#20013)

platformio.ini

@@ -55,7 +55,6 @@ lib_extra_dirs              =
                               lib/lib_div
 
 [tasmota]
-; *** Settings here do NOT affect firmware building ***
 ; Uncomment if you do NOT want gzipped map file(s)
 ;disable_map_gz = 1
 ; Uncomment and specify a folder where to place the map file(s) (default set to folder build_output)
@@ -66,6 +65,9 @@ lib_extra_dirs              =
 ;enable_esp32_gz = 1
 ; Uncomment and specify a folder where to place the firmware file(s) (default set to folder build_output)
 ;bin_dir = /tmp/bin_files/
+; Global build flags (used for all env) can be overriden in "platformio_override.ini"
+build_unflags               =
+build_flags                 =
 
 [scripts_defaults]
 extra_scripts               = pre:pio-tools/pre_source_dir.py
@@ -81,10 +83,12 @@ extra_scripts               = post:pio-tools/name-firmware.py
 ;                              post:pio-tools/obj-dump.py
                               ${scripts_defaults.extra_scripts}
 ; *** remove undesired all warnings
-build_unflags               = -Wall
+build_unflags               = ${tasmota.build_unflags}
+                               -Wall
 ;                              -mtarget-align
                               -Wdeprecated-declarations
-build_flags                 = -DCORE_DEBUG_LEVEL=0
+build_flags                 = ${tasmota.build_flags}
+                              -DCORE_DEBUG_LEVEL=0
                               -Wl,-Map,firmware.map
                               -Wno-deprecated-declarations
 ;                              -mno-target-align