use one codegen unit when compiling in dev mode

Work around for the recent change in the number of default codegen units. A proper fix requires
patching the linker script.

Author: japaric

src/05-led-roulette/Cargo.toml

@@ -8,3 +8,6 @@ pg = { path = "pg" }
 
 [profile.release]
 lto = true
+
+[profile.dev]
+codegen-units = 1

src/06-hello-world/Cargo.toml

@@ -8,3 +8,6 @@ pg = { path = "pg" }
 
 [profile.release]
 lto = true
+
+[profile.dev]
+codegen-units = 1

src/07-registers/Cargo.toml

@@ -8,3 +8,6 @@ pg = { path = "pg" }
 
 [profile.release]
 lto = true
+
+[profile.dev]
+codegen-units = 1

src/08-leds-again/Cargo.toml

@@ -8,3 +8,6 @@ pg = { path = "pg" }
 
 [profile.release]
 lto = true
+
+[profile.dev]
+codegen-units = 1

src/09-clocks-and-timers/Cargo.toml

@@ -8,3 +8,6 @@ pg = { path = "pg" }
 
 [profile.release]
 lto = true
+
+[profile.dev]
+codegen-units = 1

src/11-usart/Cargo.toml

@@ -9,3 +9,6 @@ pg = { path = "pg" }
 
 [profile.release]
 lto = true
+
+[profile.dev]
+codegen-units = 1

src/14-i2c/Cargo.toml

@@ -8,3 +8,6 @@ pg = { path = "pg" }
 
 [profile.release]
 lto = true
+
+[profile.dev]
+codegen-units = 1

src/15-led-compass/Cargo.toml

@@ -9,3 +9,6 @@ pg = { path = "pg" }
 
 [profile.release]
 lto = true
+
+[profile.dev]
+codegen-units = 1

src/16-punch-o-meter/Cargo.toml

@@ -9,3 +9,6 @@ pg = { path = "pg" }
 
 [profile.release]
 lto = true
+
+[profile.dev]
+codegen-units = 1

src/17-async-io-the-future/Cargo.toml

@@ -9,3 +9,6 @@ pg = { path = "pg" }
 
 [profile.release]
 lto = true
+
+[profile.dev]
+codegen-units = 1